Teaching Practical Physics Anywhere

Teaching Practical Physics Anywhere

2nd Edition by Joe Brock

edited by Lara Mathews

The College of Richard Collyer In association with

Acknowledgements

This book has been made possible by the combined efforts of many people.

Philip Hardy who has made the ramblings of a slightly confused physics teacher into a coherent project by finding equipment, making something new from random bits and pieces, sourcing it all for the best price, and finally checking, packaging and shipping it.

Lara Mathews who turned up out of the blue to save us. She has worked tire-lessly to try the experiments, develop them so that they work with the equipment we’re taking out, and photograph them with students. Most importantly though, she converted a book that was in Brock Font and full of scrappy diagrams into a text that is both readable and full of photos.

Mike Branfield whose calm demeanour helped to keep us all from a nervous breakdown.

Gary Mathews who produced some brilliant new diagrams for the redesigned book.

The students of who got involved, added their enthusiasm and their faces toCollyer’s the project and produced some excellent experimentation.

Pippa & Ian Howard who were the inspiration for the first book in The Gambia.

Thank you to you all.

Joe Brock

© 2013 Joe Brock (content) and the Institute of Physics (typographical arrangement)

Permission to use, copy and distribute this booklet is granted for private, non-commercial and educational

purposes only, provided that the above copyright notice appears with the following notice: This booklet may

be reprinted and distributed for non-commercial and educational purposes only, and not for resale. No resale

or use may be made of this booklet, or any part of it at any time. All other rights reserved. Logos and trade

names are included with the permission of their owners.

The Story So Far...

The main aim of this project is to bring practical physics to students regardless of where they are studying and what facilities they have available to them. This started its life as a following a conversation with a Collyer’s student who was going out to The Gambia on an educational project with a charity called PAGEANT. We supplied a minimal amount of equipment initially and hurried-ly written book. The equipment was deliberately chosen so that it could be purchased locally in the future and with the idea that

particular area of physics to a group of pupils so that they could try out the ideas that they had learnt during the day.

In this way we reached a sig-nificant number of schools in a short time. Having written a report for Physics Education the Institute of Physics decided to sponsor the project with a view to creating a model of excel-lence but this time in Tanzania. Our charity contact this time was The Friends of Amani - a centre for disabled children in Morogoro.

teachers would start to bring their own ideas to the classroom as to how they can use everyday objects to teach scientific principles. So for instance a straw can be used to show standing waves rather than an expensive and complicated series of kit such as a vibration generator and signal generator.

Having run the project in a small way for the first year the list of experiments grew, the book was rewrit-ten and we went out to The Gambia the following year. This time we ran 4 seminars where teachers from 10 different schools attended each one. Each teacher had a day’s training and was given a set of equip-ment (all basic everyday stuff) to take away with them. At the end of the day each teacher presented one

The Tanzania project initially was to ship out four boxes of equip-ment to supply four schools in the Morogoro area with a significant amount of science equipment still along the lines of everyday items that could be purchased locally in the future.

This went so well that this year we are hoping to identify and set up a training centre in Morogoro with a view to get teachers to come in from the surrounding area to learn how to use practical as the means for teaching physics. Again the intention will be that any teacher

The book has now been com-pletely redesigned by Lara Mathews incorporating photos from the project in action.

Physics is the most fascinating of subjects that can be brought to life by the imagination of teachers and students when they use practical as the way to teach ideas and applications.

attending training will return to their school with a package of equipment to help them get started with practical teaching. Morogoro is a reasonably large town a few hours drive west from Dar Es Salaam and is particularly suitable for the project as it has a number of secondary schools and a teacher training college.

The long term aim is for this to become a model for Physics education across Tanzania and to this end we are keen to show government institutions how effective and relatively inexpensive this method of teaching can be.

The College of Richard CollyerHurst Road, Horsham, RH12 2EJ

May 2010

Dear Brave Teacher,It is our pleasure to give you what we believe to be a very useful set of equipment to teach some basic and not so basic Physics.

We have tried to think of equipment that will allow you to do as many different experiments as possible and hope that some of the ideas included in this book will spark off ideas of your own.

With the equipment provided you should be able to do every experiment in the book.

We have also included some special items to inspire awe and wonder.

However, we hope that the main emphasis is on fun and the children doing as much as it is possible to do. We don’t want the equip-ment to become like a treasured possession which never comes out of its box and stays pristine for the rest of its life. Just like a useful book the equipment should be used over and over again by the children so it stays useful but looks a little battered round the edges.

Some of the very basic equipment will need replacing on a regular basis such as straws etc but we hope that you will be able to maintain your ability to teach Physics by letting the children experiment.

Good luck, we hope you will enjoy it.

Yours faithfully,

Joe BrockHead of Faculty for Science and Maths

Philip HardyScience Technician

COLLYER’S

Contents

EXP 1 FrictionEXP 2 CD HovercraftEXP 3 Forces and MotionEXP 4 Lever LawEXP 5 Pulleys as Force MultipliersEXP 6 Syringes and HydraulicsEXP 7 The Strength of ShapesEXP 8 A Paper BridgeEXP 9 Up and Down ThingsEXP 10 Centre of Mass (Gravity)EXP 11 Stability and the Centre of GravityEXP 12 Toppling the Centre of GravityEXP 13 Measuring Human Reaction TimeEXP 14 Velocity and SpeedEXP 15 Average SpeedEXP 16 Acceleration – Getting FasterEXP 17 Acceleration and MassEXP 18 A Balloon RocketEXP 19 A Water RocketEXP 20 Paper and BernoulliEXP 21 Carburettors and BernoulliEXP 22 Balancing a Pea on AirEXP 23 How Does a Plane Fly?EXP 24 EnergyEXP 25 Conduction of Different SolidsEXP 26 ConvectionEXP 27 Who is the Most Powerful Pupil?EXP 28 Making a Cotton Reel TankEXP 29 Efficiency of a Car Down a TrackEXP 30 Measuring Elastic PotentialEXP 31 Elastic Band EfficiencyEXP 32 Pressure of a Drawing PinEXP 33 Gases and PressureEXP 34 Syringes and Gas LawsEXP 35 Surface TensionEXP 36 What is a Wave?EXP 37 Ringing a BellEXP 38 Categories of WaveEXP 39 The Speed of SoundEXP 40 The Speed of Sound (Continued)EXP 41 The Range of HearingEXP 42 Record PlayerEXP 43 Rules for Ray Diagrams (Real Images)EXP 44 Rules for Ray Diagrams (Virtual Images)

EXP 45 Reflection (Continued)EXP 46 Making a PeriscopeEXP 47 Reflection ContinuedEXP 48 Images in a Plane MirrorEXP 49 RefractionEXP 50 Refraction (Continued)EXP 51 Lenses in Eyes and CamerasEXP 52 The Fluoroscein EyeEXP 53 The Pinhole CameraEXP 54 The Pinhole Camera (Continued)EXP 55 The Eye as a Pinhole CameraEXP 56 UFOs and MiragesEXP 57 Telescopes and Reflection/RefractionEXP 58 Wavelength (λ) and Frequency (f)EXP 60 Standing WavesEXP 61 Standing Waves on a GuitarEXP 62 Straw FlutesEXP 63 Making MusicEXP 64 Elephants and TubesEXP 65 The Doppler EffectEXP 66 The Doppler Effect and the Big BangEXP 67 The Big BangEXP 68 Space Telescopes vs. Terrestrial TelescopesEXP 69 How Quickly Do We Orbit the Sun?EXP 70 Leeuwenhoek’s MicroscopeEXP 71 White Light and ColourEXP 72 Invisible WritingEXP 73 A Cat’s SightEXP 74 PolarisationEXP 75 Polarising FiltersEXP 76 Polarisation on ReflectionEXP 77 Other Uses of PolarisationEXP 78 Standing Waves and BalafonsEXP 79 Young’s Double SlitsEXP 80 Measuring the Wavelength of LightEXP 81 Dice to Show Radioactive DecayEXP 82 Circular MotionEXP 83 Sticky BalloonEXP 84 Dancing CrumbsEXP 85 Bending WaterEXP 86 Attraction and RepulsionEXP 87 Hooke’s Law and the Spring Constant (k)EXP 88 Simple Harmonic Motion with a SpringEXP 89 Simple Harmonic Motion with a Pendulum

The College of Richard Collyer

Joe Brock and Lara Mathews

EXP 01Friction

Try Galileo’s thought experiment with marbles and a track.

You will need: V track and a mar-ble.

Hold the track up in a U-shape and drop the marble from one end.

T Galileo’s thought experiment marbles and a track.

You will need: V track and a mar-ble.

Hold the track up in a U-shape and drop the marble from one end.

1Try Gwith 1

If there was no friction the marble would always get to the same height on the track and it would keep moving up and down in the track forever.

There is a little friction, however, so the marble keeps rocking back and forth to almost the same height as before, and eventually it will stop.

If there was no friction the marble ld always get to the same height

on the track and it would keep moving up and down in the track forever.

There is a little friction, however, so the marble keeps rocking back and forth to almost the same height as before, and eventually it will stop.

2If thewoulon th

2

Make the track a little less steep on one side. The marble goes further along, until it gets to almost the same height on the track.

Make the track even less steep on one side. The marble goes even further until it gets to the almost same height.

M ke the track a little less steep on one side. The ble goes further along, until it gets to almost the

same height on the track.

Make the track even less steep on one side. The marble goes even further until it gets to the almost same height.

3Makmarbsame

3

Now put the track flat on one side. The marble will try to go on forever as it will never reach the same height and it has leftover energy.

Conclusion:

Even if it seems like an object will go on forever, if there is friction it will lose energy and eventually stop.

N w put the track flat on one side. The marbble will o go on forever as it will never reach the same

height and it has leftover energy.

Conclusion:

Even if it seems like an object will go on forever, if there is friction it will lose energy and eventually stop.

4Now try toheigh

4



EXP 02 CD Hovercraft

So how do we get rid of friction?

Try this CD hovercraft.

Blow up the balloon, then put it down on a flat sur-face. Give it a push – it goes for a long time!

S how do we get rid of ion?

Try this CD hovercraft.

Blow up the balloon, then put it down on a flat sur-face. Give it a push – it goes for a long time!

1So hfricti1

Conclusion: With no friction to stop something it will keep going forever.

Newton’s 1st Law: An ob-ject will continue at a con-stant velocity (or be at rest: v = 0 ms-1) if the resultant force on it is zero.

CC cllu ision: W Witith h riction to

stop something it will keep going forever.

Newton’s 1st Law: A An ob-ject will continue at a a con-stant velocity (or be aat rest: v = 0 ms-1) if the resuultant force on it is zero.

2Concno frstop

2

Air goes out hole

Air forms a cushion

Balloon

CD with lip upwards

Bung with hole



EXP 03Forces and Motion

Turning things (things that go round in a circle) also obey this law. Try this experiment:T ning things (things that go round in a circle) also

y this law. Try this experiment:2Turnobey2

So the effectiveness (moment) of a force is depend-ent on the distance of the force from the pivot. Stu-dent 2’s little finger force is able to balance student 1’s huge force because it is so much farther from the pivot. So:

Moment = force x distance from pivot

We have balance (equilibrium) when student 1’s moment equals student 2’s moment.

So the effectiveness (moment) of a force is deepend-on the distance of the force from the pivot. Stu- 2’s little finger force is able to balance sttudent

1’s huge force because it is so much farther fr rom the pivot. So:

Moment = force x distance from pivote x

We have balance (equilibrium) when student 1’s moment equals student 2’s moment.

4So thent odent

4

F1 x d1 = F2 x d2

e.g.

500N x 0.1m = 50N x 1m

F1F x d d1 d = F2 F x d d2 d

g

500N x 0.1m = 50N x 1m

5F

e.g.

In the diagram student 2’s moment is pushing the opposite way to the way a clock’s hands move, so it is called an anticlockwise moment. Student 1 is pushing the same way as a clock’s hands move so it is called a clockwise moment. For equilibrium (balance):

Anticlockwise clockwise movement = movement(ACM) (CM)

This is called lever law – and all with just a door!

In the diagram student 2’s moment is pushingg the osite way to the way a clock’s hands movve, so

it is called an anticlockwise moment. Studennt 1 is pushing the same way as a clock’s hands movve so it is called a clockwise moment. For equilibrrium (balance):

Anticlockwise clockwise movement = movement(ACM) (CM)

This is called lever law – and all with just a d door!

6In thoppoit is c

6

A force is a push or pull and is measured in New-tons (named after Isaac Newton).

Newton’s 1st Law: An object will be stationary or moving with a constant velocity if the resultant force on it is zero.

A f rce is a push or pull and is measured in N New- (named after Isaac Newton).

Newton’s 1st Law: An object will be stationary or moving with a constant velocity if the resultant force on it is zero.

1A fortons 1

Get the first student to push near to the door hinge but show that the second student can ‘balance’ the-first student’s force with just his little finger. How? Is student 2 superhuman? How could you make it more difficult for student 2? Move student 1 away from the hinge (the pivot).

5

G t the first student to push near to the door hinge show that the second student can ‘balance’ the-

first student’s force with just his little finger. How? Is student 2 superhuman? How could you make it more difficult for student 2? Move student 1 away from the hinge (the pivot).

3Get tbut sfirst

3

Resultant force = 0N

+4N-4N



EXP 04 Lever Law

Get students to try to balance two different masses by putting them at different distances from the pivot.Make up a table of situations where there is equilibrium.

G t students to try to balance two different masses utting them at different distances from the

pivot.Make up a table of situations where there is equilibrium.

1Get sby pupivot

1

So if the tin opener is not accelerating it must be in equilibrium. So the moments either side of the pivot are the same.

F1 x d1 = F2 x d2

If F2 is the force at the cutting edge and d2<<d1 then F2>>F1 i.e. F2 is large.

S if the tin opener is not accelerating it mustt be in librium. So the moments either side of thhe pivot

are the same.

F1 F x d1 d = F2 F x d2 d

If F2F is the force at the cutting edge and d2d <<<d1d then F2F >>F1F i.e. F2F is large.

7So if equilare th

7

Forces become more effective (their moment is greater) the further they are from the pivot.

If the anticlockwise moment (ACM) equals the clockwise moment (CM) there is equilibrium.

F es become more effective (their moment is ter) the further they are from the pivot.

If the anticlockwise moment (ACM) equals the clockwise moment (CM) there is equilibrium.

4Forcgreat4

Try to find equilibrium for yourself. Put a ruler on a pivot and add masses to the top.

See if you can get it to balance for yourself!

T to find equilibrium for yourself. Put a ruler on a t and add masses to the top.

See if you can get it to balance for yourself!

5Try tpivot 5

You can see on this tin opener that the distance (d1) from where the hands grip to the pivot is large com-pared to the distance to the cutting edge (d2).

Y can see on this tin opener that the distance (d1d ) m where the hands grip to the pivot is large com-

pared to the distance to the cutting edge (d2d ).6

You frompared

6

In fact F2 is so large it can easily cut through the metal of this tin.I fact F2F is so large it can easily cut through the

al of this tin.8In fameta8

F1 d1 F1 x d1 F2 d2 F2 x d2

4N 0.1m 0.4Nm 2N 0.2m 0.4Nm

Here the F1 x d1 and the F2 x d2 columns should be the same.

F d1 d F1 F x dx 1 d F2F d2 d F2 F x dx 2 d2

0.1m 0.4Nm 2N 0.2m 0.4Nm

Here the F1 F x d1d and the F2 F x d2d columns should be the same.

3F1F

4N3

Notice the distance to centre of masses:ce the distance to centre of masses:2 Notic2

F1

d1 d2

F2



EXP 05Pulleys as Force Multipliers

Let’s say we want to transfer 1200J of energy.

Energy = Force x Distance

1200J = 1200N x 1m

= 600N x 2m

= 300N x 4m

= 120N x 10m

L t’s say we want to transfer 1200J of energyy.

Energy = Force x Distance

1200J = 1200N x 1m

= 600N x 2m

= 300N x 4m

= 120N x 10m

2Let’s

E2

To transfer energy we have to apply a force over a distance.

Energy Distancetransferred = Force x moved by that force

T transfer energy we have to apply a force oover a ance.

Energy Distancetransferred = Force d x moved by that force

1To trdista1

So anything that increases the distance over which we apply the force means we need less force to transfer the energy.

NOTE: In real life there’s some friction to over-come, so the efforts will be greater than quoted.

SS nyththiing ththat i increases thhe d diistance which we apply the force means we

need less force to transfer the energy.

NOTE: In real life there’s some friction to ovver-come, so the efforts will be greater than quoteed.

4So anover need

4

Pulleys do this for us. Look what happens when we use two strings between the pulleys:

This means that whatever distance the Effort force moves the load (weight) only moves half (÷ 2 strings) that distance. So we only need 600N to lift 1200N. The effort moves twice the distance with half the force.

P lleys do this for us. Look what happens when we two strings between the pulleys:

This means that whatever distance the Effort force moves the load (weight) only moves half (÷ 2strings) that distance. So we only need 600N to lift N1200N. The effort moves twice the distance with N. The effort moves twice the distance with Nhalf the force.

5Pulleuse t5

Try the experiment using 2, 3 and 4 pulleys and see how the force needed changes.T the experiment using 2, 3 and 4 pulleys and see

the force needed changes.6Try thow 6

1200N 1200N

1m 2m

Look as we increase the distance the force required to transfer that energy gets less. This is why it is easier to push things up a ramp than to lift them directly.

Force = 1200N Force = 600Nneeded needed

41200N1200N 1200N1200N

1m 2m

L k as we increase the distance the force required ansfer that energy gets less. This is why it is

easier to push things up a ramp than to lift them directly.

Force = 1200N Force = 600Nneeded d needed

3Lookto traeasie

3

1200N

600N



EXP 06 Syringes and Hydraulics

In liquids mol-ecules are closely packed together so liquids are almost incompressible.

This means that the pressure in a liquid is the same throughout its volume, assuming there isn’t a large change in depth like there is in an ocean.

I liquids mol-es are closely

packed together so liquids are almost incompressible.

This means that the pressure in a liquid is the same throughout its volume, assuming there isn’t a large change in depth like there is in an ocean.

1In liqeculepack

1

Careful here though. We are not creating energy. The distance moved by the bigger force will be 5 times less.

Energy = Force x distancetransferred

With 5 x F and d/5 we could get the same energy out as we put in but not more. In practice there is a lot of fric-tion and energy as usual is wasted.

C ful here though. We are not creating enerrgy. distance moved by the bigger force will bbe 5

times less.

Energy = Force x distancetransferred

With 5 x F and F d/5 we could get the same energy out as we put in but not more. In practice there is a lot of fric-tion and energy as usual is wasted.

5 CarefThe dtimes

5

Hydraulic systems can be used as force multipliers. Here the output (larger) piston has 5 times the area of the input (smaller) piston.

So a 200N push on the brake pedal of a car becomes a 1000N (5 x 200N) push on the brakes.

H draulic systems can be used as force multipliers. e the output (larger) piston has 5 times the area

of the input (smaller) piston.

So a 200N push on the brake pedal of a car becomes Na 1000N (5 x 200N) push on the brakes.

3HydrHereof th

3

Remember, P = F A and the pressure is the same throughout the system.

So with 5 times the area you get 5 times the force. A small push becomes a large push.

R member, P = F A and the pressure is the same ughout the system.

So with 5 times the area you get 5 times the force. A small push becomes a large push.

4Remthrou4

Try getting one pupil to push on the big syringe and one to push on the small syringe. Even if the pupil with the big syringe is very strong, the pupil with the small syringe is going to win!

Friction prevents any useful quantifiable experimen-tation taking place.

T getting one pupil to push on the big syringe and to push on the small syringe. Even if the pupil

with the big syringe is very strong, the pupil with the small syringe is going to win!

Friction prevents any useful quantifiable experimen-tation taking place.

6Try gone twith

6

Note:

Pressure (P) = Force (F) Area (A)

so

F = P x A

N t :

Pressure (P) = Force (F)( ) Area (A)

so

F = P x A

2 Note

2



EXP 07The Strength of Shapes

There are two shapes that can make a material seem very strong – circles and triangles.

Here are a couple of experiments to help you ex-plore the possibilities.

Th re are two shapes that can make a material seem strong – circles and triangles.

Here are a couple of experiments to help you ex-plore the possibilities.

1Ther very 1

Mission 1:

Support a student 2cm off the ground using only a board of wood of approximately 30cm x 30cm and two sheets of A4 paper.

Mi sion 1:

pport a student 2cm off the ground using only a board of wood of approximately 30cm x 30cm and two sheets of A4 paper.

2Miss

Supp2

Try cutting the paper into 2cm strips and then fold-ing the paper into coiled cylinders or triangular prisms. The best shapes to use are cylinders. Just nine cylinders of 1cm diameter can support a stu-dent’s weight.

Take a little care to make them all the same height.

T cutting the paper into 2cm strips and then fold-he paper into coiled cylinders or triangular

prisms. The best shapes to use are cylinders. Just nine cylinders of 1cm diameter can support a stu-dent’s weight.

Take a little care to make them all the same height.

3Try cing thprism

3

Give students clues if they require them but they might come up with new and innovative ideas if you don’t.

Gi e students clues if they require them but they ht come up with new and innovative ideas if you

don t.4

Givemighdon’t

4

Look, this student is supported by less than one piece of A4 paper! Great!L k, this student is supported by less than one

e of A4 paper! Great!5Lookpiece 5



EXP 08 A Paper Bridge

Mission 2:

Who can make the strongest bridge between two supports 15cm apart? The supports can be books and should be about 6cm high. Pupils should all be given 3 sheets of A4 paper and a tiny amount of sticky tape.

Mi sion 2:

o can make the strongest bridge between two supports 15cm apart? The supports can be books and should be about 6cm high. Pupils should all be given 3 sheets of A4 paper and a tiny amount of sticky tape.

1Miss

Who 1

The load must not be above the supports in any way. The bridge which can support the heaviest load without collapsing is the strongest.

Th load must not be above the supports in any The bridge which can support the heaviest load

without collapsing is the strongest.2

The way. with

2

A4 paper is very strong if it is folded many times. Corrugations can be used in bridge building as they use the triangle shape. Set the mission and who knows what your students will come up with!

A4 paper is very strong if it is folded many times. ugations can be used in bridge building as they

use the triangle shape. Set the mission and who knows what your students will come up with!

3A4 pCorruse t

3A surprisingly heavy weight can be supported on just paper.A rprisingly heavy weight can be supported on

paper.4A sujust p4



EXP 09Up and Down Things

Another condition for equilibrium (balance, when the resultant force of something is zero) is when UP forces = DOWN forces.

For this experi-ment you will need:

1 metre rule• 2 Newton • meters1 set of • weightsString •

Another condition equilibrium

(balance, when the resultant force of something is zero) is when UP forces = DOWN forces.

For this experi-ment you will need:

1 metre rule•2 Newton •meters1 set of •weightsString •

1Anotfor e(bala

1

The weight of the ruler is also one of the down forces.

UP DOWN

F1 + F2 = F3 + ?

<--- Weight of rule

Th weight of the ruler is also one of the dowwn es.

UP DOWN

F1F + F2 F = F3 F + ?

<--- Weight of rule

5The force

Conclusion:

Up = Down for equilibrium.

C clusion:

p = Down for equilibrium.6

Conc

Up =6

Set up the experiment so that the string is holding up the Newton meters so that they are level, and so that the ruler is level.

S t up the experiment so that the string is holding he Newton meters so that they are level, and so

that the ruler is level.2

Set uup ththat t

2F1 and F2 are up forces. You can tell because if you remove one or the other or both then the bottom ruler falls down, so they must be pulling up. Move the weight (F3) across the bottom ruler and record the values of F1, F2 and F3.

F nd F2 F are up forces. You can tell because if you ove one or the other or both then the bottom

ruler falls down, so they must be pulling up. Move the weight (F3F ) across the bottom ruler and record the values of Ff 1 F , F2F and F3 F .

3F1F anremoruler

3

Make a table of your results:

F1 F2 F1 + F2 F3

F3 will come out a little bit less than F1 + F2. Why?

5M ke a table of your results:

1 F2F F1F + F2 F F3F

F3F will come out a little bit less than F1F + F2 F . Why?

4Mak

F1F4



EXP 10 Centre of Mass (Gravity)

When we studied moments (EXP 3) did you no-tice we looked at the distance to the centre (not the edges) of the mass? The centre of mass is a very important property. It is the point at which gravity appears to act on an object.

When we studied moments (EXP 3) did you no- we looked at the distance to the centre (not the

edges) of the mass? The centre of mass is a very important property. It is the point at which gravity appears to act on an object.

1Whetice wedge

1

To find the centre of mass of an object you will need: card, string, a weight, a pin.T find the centre of mass of an object you will

d: card, string, a weight, a pin.2To fineed2

The point where all the lines cross is the centre of gravity.

Th t

where all the lines cross is the centre of gravity.

4The point wher

4

This is what you will need to do:

Cut a strange shape out of card (letters are good).1. Poke a hole in the card with the pin and wiggle it so that it’s just loose.2. Let the card hang.3. Dangle the weight on a string from the pin and draw a line along the string on the card.4. Find another point and poke the pin through again. Repeat steps 3. and 4. The lines will cross somewhere.5. Try a third point and the string line should cross the same point.6.

is what you will need to do:

Cut a strange shape out of card (letters are good).1.Poke a hole in the card with the pin and wiggle it so that it’s just loose.2.Let the card hang.3.Dangle the weight on a string from the pin and draw a line along the string on the card.4.Find another point and poke the pin through again. Repeat steps 3. and 4. The lines will cross somewhere.5.Try a third point and the string line should cross the same point.6.

3 This 3

weight

pin

card string



Some objects have a centre of gravity that’s not actually inside the object. Think about an n or o shape.

Try the experiment again with this shape (probably good to demonstrate this to the class).

S e objects have a centre of gravity that’s not ally inside the object. Think about an n or o

shape.

Try the experiment again with this shape (probably good to demonstrate this to the class).

5Somactuashap

5

Because the jumper makes an n shape they do not have to get their centre of gravity over the bar so they can get over a higher bar and win the competition.

If they just jumped… look:

B ause the jumper makes an n shape they ot have to get their centre of gravity

over the bar so they can get over a higher bar and win the competition.

If they just jumped… look:

7Becado noover

7

Now this is particularly useful in high jump. Look at the shape high jumpers make to get over the bar. It’s called the Fosbury Flop.

w this is particularly useful in high jump. Look at the shape high jumpers make to get over the bar. It’s called Fosbury Flop.6 Now

the F6

equal in energy to



EXP 11 Stability and the Centre of Gravity

If you want an object to be stable its centre of gravity (C of G) must act through a line that is within the support points.

If ou want an object to be le its centre of gravity (C of

G) must act through a line that is within the support points.

1If yostablG) m

1

If the object is standing then the C of G must be directly above the base of the object (the part that is touching the ground) for it to be stable. If the object is hanging the C of G must be below the support point for it to be stable.

If the object is standing then the f G must be directly above

the base of the object (the part that is touching the ground) for it to be stable. If the object is hanging the C of G must be below the support point for it to be stable.

2If theC of the b

2

The object shown here is very stable as the heavy forks bring the centre of gravity to below the point where the pin touches the glue stick. You can wobble this object and despite being supported by a thin pin it will not fall over.

Th object wn here is

very stable as the heavy forks bring the centre of gravity to below the point where the pin touches the glue stick. You can wobble this object and despite being supported by a thin pin it will not fall over.

3The showvery

3

A leopard asleep in a tree. He hangs his legs, tail and head as low as he can. In this way his centre of gravity is below the top edge of the branch, so he is stable. He can sleep without fear of falling off. This one is obviously awake!

A l opard asleep in a tree. He hangs his legs, tail head as low as he can. In this way his centre of

gravity is below the top edge of the branch, so he is stable. He can sleep without fear of falling off. This one is obviously awake!

4A leoand hgravi

4

When we add masses, we make the C of G change to below the string:

C of G is now below the support point, so the pulley is stable.

When we add masses, we make the C of G change elow the string:

C of G is now below the support point, so the pulley is stable.

6Wheto be

Try this experiment – you will need a pulley with a hook, some slotted masses and some string.

The Students’ Mission: Try to get your pulley to run between two people on the string. Unfortunate-ly, the pulley keeps falling over – it is unstable. The centre of gravity is above the string (support point). What could we do to try to get the centre of gravity below the string?

6

T this experiment – you will need a pulley with a k, some slotted masses and some string.

The Students’ Mission: Try to get your pulley to run between two people on the string. Unfortunate-ly, the pulley keeps falling over – it is unstable. The centre of gravity is above the string (support point). What could we do to try to get the centre of gravity below the string?

5Try thook5



EXP 12Toppling and the Centre of Gravity

Try this C of G experiment. You will need:

A plastic bottle•

Water•

Look at how different amounts of water affect the centre of gravity and how far the bottle will tip before it falls over.

T this C of G experiment. You will need:

A plastic bottle

Water•

Look at how different amounts of water affect the centre of gravity and how far the bottle will tip before it falls over.

1Try t

A •1

Put a little water into the bottle. Push the bottle and see how far you can tip it before it topples over.P t a little water into the bottle. Push the bottle and

how far you can tip it before it topples over.2Put a see h2

Put some more water in. The centre of gravity is higher this time, so the bottle topples over more easily.

P t some more water in. The centre of gravity is er this time, so the bottle topples over more

easily.3

Put shigheeasil

3

Now fill it up completely. When the bottle is full, it topples over almost straight away. This is because the centre of gravity is high.

N w fill it up completely. When the bottle is full, it les over almost straight away. This is because

the centre of gravity is high.4

Now topplthe c

4

This toy bird has heavy weights in the ends of the wings so its centre of mass is its beak. That means it can balance on its beak and it looks like it is fly-ing!

Thi toy bird has heavy weights in the ends of the gs so its centre of mass is its beak. That means

it can balance on its beak and it looks like it is fly-ing!

6This wingit can

6

The higher the C of G the easier it is for an object to fall over.

This is why racing cars are the shape they are. Buses can topple more easily as their Cof G is higher. They can’t go round corners as quickly as racing cars.

ThTh hihi hgher t thhe C C of f G G ththe ea isier i it t iis f for an ct to fall over.

This is why racing cars are the shape they aree. Buses can topple more easily as their Cof G iis higher. They can’t go round corners as quicklly as racing cars.

5The objec5



EXP 13 Measuring Human Reaction Time

Who has the fastest reaction time and how fast is it?

There’s an equation that relates how far something falls (x) and how long it takes (t).

Who has the fastest reaction time and how fast is it?

re’s an equation that relates how far something falls (x(x) and how long it takes (t).t

1Who

Ther1

Any more than 26cm and you must have fallen asleep! Any really quick times (6cm or less) and you just had a lucky guess.

Who’s the fastest in the class and how fast are you? What does this mean when you are timing short distances on your stop clock?

Your reaction time becomes significant.

A more than 26cm and you must have fallen ep! Any really quick times (6cm or less) and

you just had a lucky guess.

Who’s the fastest in the class and how fast are you? What does this mean when you are timing short distances on your stop clock?

Your reaction time becomes significant.

6Any asleeyou j

x = ut + ½ at2

where x is how fast it falls

t is how long it takes

a is the acceleration due to gravity

u is the start velocity

In this case the start velocity is zero, so ut = 0 and we can get rid of that bit from our equation.

x = tut + ½ ½ att222tt2

re x is how fast it fallsx

t is how long it takest

a is the acceleration due to gravity

u is the start velocity

In this case the start velocity is zero, so ut = 0 0 and we can get rid of that bit from our equation.

2x

wher2

x = ½ at2

2x = at2

2x = t2

a

t = √( 2x ) a

x = ½ ½ at22t2

2x = at2t2

2x = t2t2

a

t = √( 2x ) a

(

3x

23

Now, the acceleration due to gravity is 9.81ms-2, so for a given distance we can calculate how long it takes to fall.

N w, the acceleration due to gravity is 9.81ms-2, so a given distance we can calculate how long it

takes to fall.4

Nowfor a takes

4The ruler test: Get a friend to hold a ruler so that the 0 mark is level with the top of your hand. When they let go try tograb the ruler as quick as you can. Use the table below to see your reaction time.

Reading/cm Time/s6 0.118 0.1310 0.1412 0.1614 0.1716 0.1818 0.1920 0.2022 0.2124 0.2226 0.23

6

4Th ruler test: Get a friend to hold a ruler so that

0 mark is level with the top of your hand. When they let go try tograb the ruler as quick as you can. Use the table below to see your reaction time.

Reading/cmg Time/s6 0.118 0.1310 0.1412 0.1614 0.1716 0.1818 0.1920 0.2022 0.2124 0.2226 0.23

5The rthe 0 they

5



EXP 14Velocity and Speed

Who is the fastest? You will need a sports tape measure and stop clocks.

Measure out a distance to run with the tape 1. measure (50 to 100m).

Time each student with a few stop clocks.2.

Show that taking an average of the times is a 3. good idea. Talk about ignoring the times where someone has made a mistake (this is called an anomalous result).

Who is the fastest? You will need a sports tape sure and stop clocks.

Measure out a distance to run with the tape 1.measure (50 to 100m).

Time each student with a few stop clocks.2.

Show that taking an average of the times is a 3.good idea. Talk about ignoring the times where someone has made a mistake (this is called an anomalous result).

1Who meas1

How do we work out the speed?

Speed = distance time

e.g.

100m = 5 ms-1 20s

H w do we work out the speed?

Speed = distancetime

e.g.

100m = 5 ms-1 20s

3How

S3

Record the results in a table like this one:

Time 1 Time 2 Time 3 Average

Fred

Isobel

Andrew

R ord the results in a table like this one:

Time 1 Time 2 Time 3 Average

Fred

Isobel

Andrew

2Reco

2

It might be nice to show here how quickly a cheetah might cover this distance.

(Cheetah max. speed ≈ 26 ms-1).

Velocity is just speed with direction i.e. you have to say whether it’s + or - .

- 5 ms-1 + 5 ms-1

It ight be nice to show here how quickly a cheetah ht cover this distance.

(Cheetah max. speed ≈ 26 ms-1).

Velocity is just speed with direction i.e. you have to say whether it’s + or - .

- 5 ms-1 + 5 ms-1

4It mimigh4



EXP 15 Average Speed

In fact, when you work out a speed you are work-ing out an average speed. If you think about it, when you do a race against time you go slowest at the start, you get faster, reach maximum speed then carry on at maximum speed.

I fact, when you work out a speed you are work-out an average speed. If you think about it,

when you do a race against time you go slowest at the start, you get faster, reach maximum speed then carry on at maximum speed.

1In faing owhen

1Try to measure instantaneous speed (use a sports tape measure and four stop clocks).

Position students along the 100m with their stop clocks and get them to shout ‘stop’ when they stop their clocks as the runner goes past.

T to measure instantaneous speed (use a sports measure and four stop clocks).

Position students along the 100m with their stop clocks and get them to shout ‘stop’ when they stop their clocks as the runner goes past.

2Try ttape 2

This way the next person can start their stop clock then shout ‘stop’ when the runner goes past again.

speed = 25m time

In fact, to get instantaneous speed you need to time over tiny distances. Where is the runner going fastest?

Thi way the next person can start their stop clock then shout ‘stop’ when the runner goes past again.

speed = 25m timeed

In fact, to get instantaneous speed you need to time over tiny distances. Where is the runner going fastest?

4This

s4

Set up the experiment like this:S t up the experiment like this:3

Set u3

START

25m 25m 25m 25m



EXP 16Acceleration - Getting Faster

Try this experiment accelerating a toy car. You will need:

Toy racing cars• Track• Blu Tack• 2 stacks of slotted masses• Elastics•

T this experiment accelerating a toy car. You will d:

Toy racing cars•Track•Blu Tack•2 stacks of slotted masses•Elastics•

1Try tneed1

Conclusion:

If more force is applied the car accelerates more. Acceleration is proportional to force:

a F

This is Newton’s 2nd law of motion.

C clusion:

ore force is applied the car accelerates more. Acceleration is proportional to force:

a F

This is Newton’s 2nd law of motion.

4Conc

If mo

Now try pulling it back by the same amount, but use two elastics instead. Now you’ve applied twice the force. How does it accelerate now?

Try it again with 3 elastics on the bridge. How does it accelerate now?

How about with 4?

4N w try pulling it back by the same amount, but use

elastics instead. Now you’ve applied twice the force. How does it accelerate now?

Try it again with 3 elastics on the bridge. How does it accelerate now?

How about with 4?

3Now two eforce

3

Make an elastic bridge using one elastic and both of the slotted mass stacks. Put some Blu Tack on the back of the car to help weigh it down. Pull the car back by about 3cm and then let go. Make sure when you pull the car back that the elastics start off taut and that the masses are evenly placed on each side of the track.

M ke an elastic bridge using one elastic and both he slotted mass stacks. Put some Blu Tack on

the back of the car to help weigh it down. Pull the car back by about 3cm and then let go. Make sure when you pull the car back that the elastics start off taut and that the masses are evenly placed on each side of the track.

2Makof ththe b

2

Something else affects the acceleration of the car – what is it?S ething else affects the acceleration of the car –

t is it?5Somwhat5



EXP 17 Acceleration and Mass

This time we’re going to see what happens if you change the mass. You will need:

Toy racing cars• Track• Blu Tack• 2 stacks of slotted masses• Elastics• Ball bearings•

Thi time we’re going to see what happens if you nge the mass. You will need:

Toy racing cars•Track•Blu Tack•2 stacks of slotted masses•Elastics•Ball bearings•

1This chan1

In fact, acceleration is:

a force mass

or

a = F m

with the right units.

I fact, acceleration is:

a forcef mass

or

a = F m

with the right units.

4In faSo, with more Blu Tack (i.e. more mass) the accel-

eration will be less.

As mass goes up acceleration goes down. Accelera-tion is inversely proportional to mass

a 1 m

4S with more Blu Tack (i.e. more mass) the aaccel-

on will be less.

As mass goes up acceleration goes down. Acccelera-tion is inversely proportional to mass

a 1 m

3So, weratio3

Choose how many elastics you will use on 1. the bridge. Do not change this once you have started the experiment! Two is a good sugges-tion.

Add Blu Tack to the car Then pull it back about 2. 3cm and let it go.

Now stick a ball bearing on the front of the car 3. using the Blu Tack. Pull it back again and let it go. So, how does it accelerate this time?

Keep trying, adding more and more ball bear-4. ings each time.

Choose how many elastics you will use on 1the bridge. Do not change this once you have started the experiment! Two is a good sugges-tion.

Add Blu Tack to the car Then pull it back about 2.3cm and let it go.

Now stick a ball bearing on the front of the car 3.using the Blu Tack. Pull it back again and let it go. So, how does it accelerate this time?

Keep trying, adding more and more ball bear-4.ings each time.

2C1.ts

2



EXP 18A Balloon Rocket

To make a balloon rocket you will need a balloon, a piece of paper, sticky tape and string.

If students make these you could set up a com-petition to see whose bal-loon rocket is the fastest.

T make a balloon rocket will need a balloon,

a piece of paper, sticky tape and string.

If students make these you could set up a com-petition to see whose bal-loon rocket is the fastest.

1To myou wa pie

1

Newton’s 3rd Law:

Every force has an equal and opposite force.

These pairs of forces are always the same type of force, same size of force, act for the same time in the same plane and act on different objects in op-posite directions.

NN twton’’s 3 3 drd L Law:

ry force has an equal and opposite force.

These pairs of forces are always the same typpe of force, same size of force, act for the same timme in the same plane and act on different objects in n op-posite directions.

6New

Eve

Roll the paper up into a cylinder and use the sticky tape rolled back on itself to stick the balloon and the paper together.Blow up the balloon, thread the string through the paper and get ready to let go of (launch) the balloon.

R ll the paper up into a nder and use the sticky

tape rolled back on itself to stick the balloon and the paper together.Blow up the balloon, thread the string through the paper and get ready to let go of (launch) the balloon.

2Roll cylintape

2

The balloon rocket shows that before release the total momentum is zero because it’s not moving. After release the total momentum is still zero as the balloon has positive momentum and the air has an equal amount of negative momentum. So the total is still zero.

Th balloon rocket shows that before release the total momentum ro because it’s not moving. After release the total momentum

is still zero as the balloon has positive momentum and the air has an equal amount of negative momentum. So the total is still zero.

3The bis zeris sti

3

An alternative explanation is that the balloon ap-plies a force to the air forcing it out backwards. The air in turn applies and equal amount of force on the balloon pushing the balloon forwards.

6A alternative explanation is that the balloon ap-

s a force to the air forcing it out backwards. The air in turn applies and equal amount of force on the balloon pushing the balloon forwards.

5An aplies air in

5

In collisions and explosions momen-tum is always conserved i.e. it is the same afterwards as it was before.

I ollisions and explosions momen-is always conserved i.e. it is the

same afterwards as it was before.4

In cotum same

4



EXP 19 A Water Rocket

Have a go at making this great water rocket!

Fill the rocket bottle with water and then attach to the pump via the tube. Start to pump air into the rocket using the pump. You will know if this is happening correctly if you can see the air bubbling through the water. Keep pumping until the rocket shoots off.

A foot or hand pump may be used.

H e a go at making this t water rocket!

Fill the rocket bottle with water and then attach to the pump via the tube. Start to pump air into the rocket using the pump. You will know if this is happening correctly if you can see the air bubbling through the water. Keep pumping until the rocket shoots off.

A foot or hand pump may be used.

1Havegreat 1

Careful here, do not get above the rocket.

Stand well away!

Careful here, do not get above the rocket.

d well away!3

Care

Stan 3

Try filling with varying amounts of water, i.e. quar-ter full, half full etc. Get the pupils to predict what will happen by varying the amounts of water.

3T filling with varying amounts of water, i.e. quar-

ull, half full etc. Get the pupils to predict what will happen by varying the amounts of water.

2Try fiter fuwill h

2

Newton’s 3rd law offers an explanation. When the pressure is too much for the tube to stay in the bot-tom of the rocket, the rocket pushes water down out of the bottle. The equal but opposite force pushes the rocket up therefore making it launch into the air.

N wton’s 3rd law offers an explanation. When the sure is too much for the tube to stay in the bot-

tom of the rocket, the rocket pushes water down out of the bottle. The equal but opposite force pushes the rocket up therefore making it launch into the air.

4Newpresstom

4Talk about the problems faced by rocket engineers. A rocket has to have enough fuel, but the problem is it also has to lift the fuel too. A real dilemma!

T lk about the problems faced by rocket engineers. cket has to have enough fuel, but the problem

is it also has to lift the fuel too. A real dilemma!5

Talk A rocis it a

5

Cut a straw half way through, bend it and place it in a glass of water. If you blow very hard a low pressure is created above the break in the straw and atmospheric pressure pushes water up the tube. The fast flowing air then breaks it into a fine mist. The mist has a large surface area to volume ratio which makes it excellent for a fast reaction such as an ex-plosion. This is how carburettors work in a car with the water replaced with petrol.

DO NOT do this with petrol - it is extreme-ly dangerous.

Cut a straw half way through, bend it and plaace a glass of water. If you blow very hard a low

pressure is created above the break in the straaw and atmospheric pressure pushes water up the tubbe. The fast flowing air then breaks it into a fine mist. . The mist has a large surface area to volume ratio wwhich makes it excellent for a fast reaction such as a an ex-plosion. This is how carburettors work in a caar with the water replaced with petrol.

DO NOT do this with petrol - it is extreme-ly dangerous.

1Cut a it in press

1




EXP 20

EXP 21

Paper and Bernoulli

Carburettors and Bernoulli

Take a piece of paper and place it in front of your mouth. As expected, it dangles down.T ke a piece of paper and place it in front of your

th. As expected, it dangles down.1Takemout1

Blow hard above the paper. The fast flowing air cre-ates a low pressure and the paper is forced upwards by the greater pressure below. This is called the Bernoulli Effect.

Bl w hard above the paper. The fast flowing air cre- a low pressure and the paper is forced upwards

by the greater pressure below. This is called the Bernoulli Effect.

2Blowates by th

2



EXP 22 Balancing a Pea on Air

Can you balance a pea in an air stream? You will need a straw, a pea (or similar) and a good pair of lungs.

Blow hard, but make sure the pea can’t go down the straw.

You don’t want it going down your wind pipe!

Can you balance a pea in an air stream? You wwill d a straw, a pea (or similar) and a good paair of

lungs.

Blow hard, but make sure the pea can’t go down the straw.

You don’t want it going down your wind pipee!

1Can need lungs

1

See if you can balance the pea at an angle.S if you can balance the pea at an angle.3

See i3

It’s easier with a bendy straw.It’ easier with a bendy straw.2

It’s e2

But why doesn’t the pea just topple off to the side?

This low pressure effect (the Bernoulli Principle) takes over again.

B t why doesn’t the pea just topple off to the side?

low pressure effect (the Bernoulli Principle) takes over again.

4But w

This 4

The pea wobbles left and right. Here the pea is to the left and so the fast air is to the right of it. The fast moving air creates low pressure. The still air to the left is at a higher pressure. This pushes the pea right, back into the air column.

Th pea wobbles left and right. Here the pea is to eft and so the fast air is to the right of it. The

fast moving air creates low pressure. The still air to the left is at a higher pressure. This pushes the pea right, back into the air column.

5The pthe lefast m

5Here the pea is to the right and so the fast air is to the left of it. The fast moving air creates low pres-sure. The still air to the right is at a higher pressure. This pushes the pea left, back into the air column again. So the pea wobbles back and forth but stays in the air flow.

H e the pea is to the right and so the fast air is to eft of it. The fast moving air creates low pres-

sure. The still air to the right is at a higher pressure. This pushes the pea left, back into the air column again. So the pea wobbles back and forth but stays in the air flow.

6Herethe lesure

6



EXP 23How Does a Plane Fly?

A plane is held up by air molecules. Again it’s all down to the Bernoulli Principle.

The plane wing has a special shape in section (when you cut through it). It’s called an aerofoil.

Air is forced to flow faster over the top. Air flows more slowly underneath as it has less distance to travel in the same time.

A lane is held up by air molecules. Again it’s all n to the Bernoulli Principle.

The plane wing has a special shape in section (when you cut through it). It’s called an aerofoil.

Air is forced to flow faster over the top. Air flows more slowly underneath as it has less distance to travel in the same time.

1A pladown1

The faster the air flow the greater the force pushing the plane upwards, i.e. the greater the LIFT.Th faster the air flow the greater the force pushing

plane upwards, i.e. the greater the LIFT.3The fthe p3

Faster planes have a less obvious aerofoil. When they fly more slowly they can’t get enough lift from their wings so they fly at an angle with their nose pointed up. Unfortunately this air also acts to push the plane backwards and so slows it down.

F ter planes have a less obvious aerofoil. When fly more slowly they can’t get enough lift from

their wings so they fly at an angle with their nose pointed up. Unfortunately this air also acts to push the plane backwards and so slows it down.

4Fastethey their

4Have a go at making your own paper plane from one sheet of A4 - there are instructions at the back of the book!

H e a go at making your own paper plane from sheet of A4 - there are instructions at the back

of the book!5

Haveone sof th

5

This means the molecules have more collisions underneath the wing than on top so there is higher pressure underneath than on top and the wing is forced upwards.

Thi means the molecules have more collisions erneath the wing than on top so there is higher

pressure underneath than on top and the wing is forced upwards.

2This undepress

2



EXP 24 Energy

Energy can be stored. Stored energy is called poten-tial energy (PE). Stretched or squashed things store elastic PE. Food and fuels store chemical PE.

Things at a height store gravitational PE.

E rgy can be stored. Stored energy is called poten- energy (PE). Stretched or squashed things store

elastic PE. Food and fuels store chemical PE.

Things at a height store gravitational PE.

2Enertial eelast

2Energy is indestructible – you can’t make it or destroy it.

When we use energy it changes from one form to another. Each time it changes some energy is wasted. Energy is like money - as it spreads out it becomes less useful.

EE rgy i is iindde tstru tctibiblle – you can’t’t m kake destroy it.

When we use energy it changes from one form m to another. Each time it changes some energyy is wasted. Energy is like money - as it spreads o out it becomes less useful.

1Enerit or 1

This toy bow and arrow converts Elastic PE to ki-netic energy (KE).

Thi toy bow and w converts

Elastic PE to ki-netic energy (KE).

3This arrow Elast

3 This cell stores chemical PE.

The energy will convert to electri-cal energy if the cell is put in a circuit.

Thi cell stores mical PE.

The energy will convert to electri-cal energy if the cell is put in a circuit.

4This chem4

This candle converts chemi-cal PE in the wax to thermal energy (heat) and light.

Thi candle verts chemi-

cal PE in the wax to thermal energy (heat) and light.

5This convcal P

5This school elec-tric car’s battery converts chemical PE to KE.

Thi school elec- car’s battery

converts chemical PE to KE.

6This tric cconv

6

This microphone changes sound energy to electri-cal energy.

Thi microphone nges sound

energy to electri-cal energy.

7This chanenerg

7 The wind up mechanism in this old clock stores elastic PE and converts it to KE very slowly.

Th wind up hanism in this

old clock stores elastic PE and converts it to KE very slowly.

8The mechold c

8



EXP 25

EXP 26

Conduction of Different Solids

Convection

Metals are good conductors of heat as their elec-trons are free to move around. This means they can pass on the energy easily. Other materials lock their electrons into position so are poor conductors of heat.

M tals are good conductors of heat as their elec-s are free to move around. This means they can

pass on the energy easily. Other materials lock their electrons into position so are poor conductors of heat.

1Metatrons pass

1See how different metals conduct heat for yourself! Get some rods of metal with one end painted black, and lay them down in a line so that the painted bit is in the sun and the unpainted bit is in shadow.

S how different metals conduct heat for yourself! some rods of metal with one end painted black,

and lay them down in a line so that the painted bit is in the sun and the unpainted bit is in shadow.

2See hGet sand l

2

Which conducts the heat energy the quickest? Feel the ends of each rod to feel which is the best conductor.

Which conducts heat energy the

quickest? Feel the ends of each rod to feel which is the best conductor.

3Whicthe hquick

3

Cut out a spiral of paper and attach a piece of cotton to the centre.

C t out a spiral of er and attach a

piece of cotton to the centre.

1Cut opape piece

1

Is it warm, i.e. a good conductor?

OUCH! TOO HOT!

Is it cool, i.e a poor conductor?

NO PAIN!

I it warm, i.e. a good ductor?

OUCH! TOO HOT!

Is it cool, i.e a poor conductor?

NO PAIN!

4Is it wcond4

Hold the spiral above something hot (a black metal plate in the sun is good).

H ld the spiral ve something

hot (a black metal plate in the sun is good).

2Holdabovhot (

2

Convection only occurs in fluids (gases and liquids) because the molecules have either no force or very weak forces between them and so are free to spread out or squash back together.

C vection only occurs in fluids (gases and liquids) ause the molecules have either no force or very

weak forces between them and so are free to spread out or squash back together.

4Convbecaweak

As the hot plate heats the air above it the spaces be-tween molecules increases and the air becomes less dense. It starts to ‘float’ upwards above the more dense air surrounding it. This is called convection. Cooler volumes of fluid will sink as they are denser than the surroundings.

4A the hot plate heats the air above it the spaces be-

en molecules increases and the air becomes less dense. It starts to ‘float’ upwards above the more dense air surrounding it. This is called convection. Cooler volumes of fluid will sink as they are denser than the surroundings.

3As thtweedens

3



EXP 27 Who is the Most Powerful Pupil?

Pupils can be made to gain grav-itational potential energy (GPE) by making them stand on a stool or chair.

P ils can made to

gain grav-itational potential energy (GPE) by making them stand on a stool or chair.

1Pupibe mgain

1GPE gained = mass x g x height

GPE = mgh

where g= 9.81ms-2

PGPE E gaiin ded = mass x g x h h iei hght

GPE = mgh

where g= 9.81ms-2

2G

G2

Total no. ofenergy = GPE gained stepstransf- each step x in aerred minute

For example:

Total energy = 200J x 16 steps

= 3200J

TTotal l no. fofenergy = GPE gained stepstransf- each step x x in aerred minute

For example:

Total energy = 200J x 16 steps

= 3200J

6Tet

6Pupils should step up and down as many times as they can in one minute (60seconds).

GPE gained each step = mgh

For example:

GPE = 40kg x 9.81 x 0.5m

= 200 Joules

Note: No cheating, the pupil has to stand up straight legged.

P ils should step up and down as many timees as can in one minute (60seconds).

GPE gained each step = mgh

For example:

GPE = 40kg x 9.81 x 0.5m

= 200 Joules

Note: No cheating, the pupil has to stand up straight legged.

5Pupithey 5

Power = Total energy Time

= 3200 60

= 53.3 Js-1

= 53.3 W

PPower = TTotal l energy gy Time

= 3200 60

= 53.3 Js-1

= 53.3 W

7P 7

The height of the chair should be measured in metres (m).One student should measure exactly one minute on a stop watch.

One student should hold the chair to make sure it does not fall over!

The height of the chair should be measured in n es (m).One student should measure exacttly one

minute on a stop watch.

One student should hold the chair to make sure it does not fall over!

3The hmetrminu

3

The active student should step up on the chair, stand up straight, and then step back down again.

Th active ent should

step up on the chair, stand up straight, and then step back down again.

4The studestep

4

So who is the most powerful pupil?

Some pupils may have more mass but move slowly.

Some may be lighter but move more quickly.

S who is the most powerful pupil?

e pupils may have more mass but move slowly.

Some may be lighter but move more quickly.

8So w

Som8



EXP 28Making a Cotton Reel Tank

A cotton reel tank is a machine that converts elastic potential energy (EPE) into kinetic energy (KE).A tton reel tank is a machine that converts elastic

ntial energy (EPE) into kinetic energy (KE).1A copoten1

To make a cotton reel tank you will need a match-stick, elastic band, a piece of candle, and either a second match or a wooden dowel.

T make a cotton reel tank you will need a match-k, elastic band, a piece of candle, and either a

second match or a wooden dowel.2

To msticksecon

2

Cut a grove in the candle piece to hold the dowel or match. Thread the elastic band through the middle of the reel (a paper clip is useful here).

C t a grove in the candle piece to hold the dowel or ch. Thread the elastic band through the middle

of the reel (a paper clip is useful here). 3

Cut a matcof th

3

Pull the band through.P ll the band through.4

Pull 4

Slot the match through on the far side, wind it up and watch it go. You could even have races to see which tank can convert from EPE to KE the quick-est i.e. which is the most powerful.

Sl t the match through on the far side, wind it up watch it go. You could even have races to see

which tank can convert from EPE to KE the quick-est i.e. which is the most powerful.

5Slot and wwhic

5

Here is a two-match version which works just as well.H e is a two-match version which works just as

.6Herewell.6



EXP 29 Efficiency of a Car Down a Track

You will need a toy car, a track, a ruler, stop watch, scales or read the mass of car from sticker under-neath it.

Y will need a toy car, a track, a ruler, stop watch, es or read the mass of car from sticker under-

neath it.1

You scaleneath

1

Total energy in = GPE

Useful energy out = KE

Efficiency = Useful Out x 100% Total In

= KE x 100% GPE

TTotal l energy i in = GPGPEE

Useful energy out = KE

Efficiency = Useful Outf t x 100% Total In x 100%

= KE x 100% GPE

5T

U5

The car has GPE at the top of the slope where

GPE = mgh

Th car has GPE at the top of the slope where e

GPE = mgh3

The

G3

Set up your track and mark out 1m along the hori-zontal section. Measure the height (h) of the car at the top of the slope.

S t up your track and mark out 1m along the hori-al section. Measure the height (h) of the car at

the top of the slope.2

Set uzontathe to

2

Energy cannot be made or destroyed so where’s the energy gone? It has been transferred to thermal energy via the force of friction.

E rgy cannot be made or destroyed so where’s energy gone? It has been transferred to thermal

energy via the force of friction.6

Enerthe eenerg

6

The car has KE along the horizontal section where KE = 0.5mv2. Velocity can be calculated using v=x/t where x = 1m and t is measured on the stop watch.

Th car has KE along the horizontal section where E = 0.5mv2. Velocity can be calculated using v=x/t

where x = 1m and t is measured on the stop watch.t4

The KE =wher

4



EXP 30Measuring Elastic Potential

In this experiment students will find the amount of EPE stored in an elastic band, measure how much of it can be converted into GPE via KE and finally work out how efficient it is at converting energy.

I this experiment students will find the amount of stored in an elastic band, measure how much

of it can be converted into GPE via KE and finally work out how efficient it is at converting energy.

1In thEPE of it

1

The area represents the energy, stored as elastic potential energy, that can be recovered (translated).

Area = ½ base x height

= ½ Fx

Th area represents the energy, stored as elasttic ntial energy, that can be recovered (transllated).

Area = ½ base x height

= ½ Fx

6The poten6

Load the elastic band with a number of weights from 1N to 10N. For each weight (F) measure the exten-sion (x) (the difference between its loaded length and its original length at the start).

Repeat the experiment, but now unload it from 10N to 1N.

Record both loading and unloading exten-sions.

L d the elastic band a number of

weights from 1N to 10N. For each weight (F) measure the extenF -sion (x ) (the difference between its loaded length and its original length at the start).

Repeat the experiment, but now unload it from 10N to 1N.

Record both loading and unloading exten-sions.

3Loadwith weig

3

Measure the un-stretched length of an elastic band by pulling it gently down.

M sure un-

stretched length of an elastic band by pulling it gently down.

2Measthe ustretc

2

The area can most easily be calculated by approxi-mating the curve to a triangle where area lost equals area gained. The energy stored is the area under the triangle.

Th area can most easily be calculated by approxi-ng the curve to a triangle where area lost equals

area gained. The energy stored is the area under the triangle.

5The matinarea

5

The area under the unloading curve is the energy available for flicking.Th area under the unloading curve is the energy

lable for flicking.4The avail4

F/N

x/m

energy available for flicking

loading

unloading

F/N

x/m

area gained

area lost

estimatin

g line



EXP 31 Elastic Band Efficiency

This is good fun. Get the pupils to flick an elastic band from the top of the ruler to the ceiling. When they get the band to touch the ceiling they should make a note of the extension (x) required to get it to do this.

Thi is good fun. Get the pupils to flick an elastic d from the top of the ruler to the ceiling. When

they get the band to touch the ceiling they should make a note of the extension (x (x ) required to get it to do this.

1This bandthey

1

Measure the mass of 100 similar elastic bands and divide by 100 to get the mass (m) of one of them. Calculate GPE:

GPE = mgh

where h is the height from the top of the ruler to the ceiling (see box 3) and g = 9.81 ms-2

M sure the mass of 100 similar elastic bands and de by 100 to get the mass (m) of one of thhem.

Calculate GPE:

GPE = mgh

where h is the height from the top of the ruler r to the ceiling (see box 3) and g = 9.81 ms-2

4MeasdividCalc

4

Calculate the Elastic PE by estimating a triangular area.

Efficiency = GPE x 100% EPE

C l ulate the Elastic PE by estimating a trianngular

Efficiency = GPE x 100% EPE

5Calcarea.5

Watch out! The band should touch the ceiling very gently, not bash into it.

W tch The

band should touch the ceiling very gently, not bash into it.

2Watcout! band

2

Measure the height between the top of the ruler and the ceiling (h).

M sure height

between the top of the ruler and the ceiling (h).

3Measthe hbetw

3

energy stored in the band at this extension

extension needed to just touch the ceiling

F/N

x/m

So the student is happy but the teacher is not. The teacher is experiencing a lot of pressure. The same force is applied but the contact area for the teacher is smaller than for the student.

Pressure = Force Area

Units in in Nm-2

S the student is happy but the teacher is not. The her is experiencing a lot of pressure. The same

force is applied but the contact area for the teeacher is smaller than for the student.

Pressure = Force Area

Units in in Nm-2

5So thteachforce

5



EXP 32Pressure of a Drawing Pin

What’s the difference between force and pressure? Show the students a large weight (heavy rock or book) and a drawing pin. Then ask for a volun-teers...

Do not actually do what’s next!

What’s the difference between force and presssure? w the students a large weight (heavy rockk or

book) and a drawing pin. Then ask for a volun-teers...

Do not actually do what’s next!

1WhaShowbook

1

When the teacher tries to hold up the object it hurts!

There is a lot of pressure here. There is a large weight, so a large force but there is also very little contact area at the point of the pin.

When the teacher tries to hold up the object it hurts!

re is a lot of pressure here. There is a large weight, so a large force but there is also very little contact area at the point of the pin.

3Whe

Ther 3

Choose a student.

Imagine you have to hold up the heavy object by balancing it on a drawing pin. The teacher has to have a drawing pin facing down, and the student gets a drawing pin facing up.

The student is lucky and the teacher is unlucky.

Ask them if they know why.

Ch ose a student.

gine you have to hold up the heavy object by balancing it on a drawing pin. The teacher has to have a drawing pin facing down, and the student gets a drawing pin facing up.

The student is lucky and the teacher is unlucky.

Ask them if they know why.

2Choo

Imag2

Now the student tries, and it’s fine. Painless!

There is not much pressure here. There is still a large weight and so large force but there is a large contact area at the head of the pin.

N w the student tries, and it’s fine. Painless!

re is not much pressure here. There is still a large weight and so large force but there is a large contact area at the head of the pin.

4Now

Ther 4

A sharp knife has less contact area with the thing it is cutting so for a given force the pressure is greater. So a sharp knife cuts more easily. Eskimos’ snow shoes and camels’ feet (that stop them sinking into the snow or sand) are examples of more area, so less pressure.

A harp knife has less contact area with the thing it utting so for a given force the pressure is greater.

So a sharp knife cuts more easily. Eskimos’ snow shoes and camels’ feet (that stop them sinking into the snow or sand) are examples of more area, so less pressure.

6A shis cuSo a

6



EXP 33 Gases and Pressure

So an increase in temperature (T) leads to an increase in pressure (p) enough to blow the lid off. In fact if we measure temperature in Kelvin (rather than ºC) then double the temperature gives double the pressure.

In fact: Pressure is proportional to Temperature for a fixed volume and mass of gas

p = constant x T

S n increase in temperature (T) leads to an T) leads to an Tease in pressure (p (p ) enough to blow the lid off.

In fact if we measure temperature in Kelvin (rather than ºC) then double the temperature gives doouble C) then double the temperature gives double the pressure.

In fact: Pressure is proportional to Temperatuure for a fixed volume and mass of gas

p = constant x T

7So an increIn fa

7

Gases exert a pressure because their molecules are whizzing around and bashing into the surface of the container that holds them. As they hit they apply a force over an area.

Pressure = force area

so the molecules exert a pressure.

The ball shown here applies a force over the area of the floor and so acts like molecules bashing against a container wall.

G es exert a pressure because their moleculees are zzing around and bashing into the surfacee of the

container that holds them. As they hit they appply a force over an area.

Pressure = forcef area

so the molecules exert a pressure.

The ball shown here applies a force over the a area of the floor and so acts like molecules bashing aagainst a container wall.

1Gasewhizconta

1

We could increase the speed of the molecules so they hit the container harder and more often. We could do this by increasing the temperature of the gas (make it hotter).

W could increase the speed of the molecules so hit the container harder and more often. We

could do this by increasing the temperature of the gas (make it hotter).

3We cthey could

3

We could reduce the area over which the molecules are hitting the walls. We could do this by squeezing the container that holds the gas, i.e. reduce the volume of the container.

W could reduce the over which the

molecules are hitting the walls. We could do this by squeezing the container that holds the gas, i.e. reduce the volume of the container.

4We carea mole

4

Note that you will probably have to put in a little water to help increase the volume. This is because water increases a lot in volume when it turns to steam. This helps increase the pressure enough to blow the lid off and it happens a lot more quickly.

N te that you will probably have to put in a little er to help increase the volume. This is because

water increases a lot in volume when it turns to steam. This helps increase the pressure enough to blow the lid off and it happens a lot more quickly.

6Notewate wate

6

There are three ways for a gas to exert more pres-sure. We could introduce more molecules. More molecules would hit more often and so increase pressure exerted. We could do this by pumping more gas into a container.

Th re are three ways for a gas to exert more pres-. We could introduce more molecules. More

molecules would hit more often and so increase pressure exerted. We could do this by pumping more gas into a container.

2Ther sure. mole

2

You can increase the speed of the molecules by increasing their temperature.

Here we are heating a sweet tin enough to blow the top off. This could just as easily be done on a fire,

but don’t get above it!

You can increase the speed of the molecules bby easing their temperature.

Here we are heating a sweet tin enough to bloow the top off. This could just as easily be done on a a fire,

but don’t get above it!

5You incre5



EXP 34Syringes and Gas Laws

Trap a fixed amount of air inside a syringe by plac-ing your finger over the end. We now have a fixed amount of gas molecules as they can’t escape.

T a fixed amount of air inside a syringe by plac-your finger over the end. We now have a fixed

amount of gas molecules as they can’t escape.1

Trap ing yamou

1

What will happen to the pressure (p) inside the sy-ringe if you squeeze the syringe to half its volume?

Halving the volume doubles the pressure – you can feel it pushing back.

What will happen to the pressure (p) inside the sy-e if you squeeze the syringe to half its volume?

Halving the volume doubles the pressure – you can feel it pushing back.

2Wharinge 2

So the equation for a fixed mass of gas at a constant temperature is:

pV = constant

It is named Boyle’s Law after Robert Boyle.

S the equation for a fixed mass of gas at a coonstant perature is:

pV = constant

It is named Boyle’s Law after Robert Boyle.

7So thtemp

Look:

p x 2 x V x ½ = pV

p x 4 x V x ¼ = pV

For a fixed mass of gas at a constant temperature the relationship is always the same.

L k:

p x 2 x V x ½ = pV

p x 4

7

x V x ¼ = pV

For a fixed mass of gas at a constant temperatture the relationship is always the same.

6Look

p 6

What if you squeeze the syringe to ¼ its original volume? Pressure will be 4 times more.

Look:

V x ½ , p x 2

V x ¼ , p x 4

Can you see the relationship?

What if you squeeze the syringe to ¼ its origiinal me? Pressure will be 4 times more.

Look:

V x ½ , p x 2

V x ¼ , p x 4

Can you see the relationship?

4Whavolum4

The famous scientist Robert Boyle spotted it. He saw that for a fixed amount of gas molecules:

pV = constant value

Th famous scientist Robert Boyle spotted it. He that for a fixed amount of gas molecules::

pV = constant value

5The saw 5

If we quarter the volume the pressure goes up by 4 times. You can really feel it now!If e quarter the volume the pressure goes up by 4

s. You can really feel it now!3If we times3



EXP 35 Surface Tension

Look at how drops of water form on certain plants. The surface tension pulls water into the simplest shape – a perfect sphere – a shape of least surface area/volume ratio.

This same surface tension pulls water up thin tubes. This is called capillary action and plants use it to help them transport liquids up and down the stem.

Look at how drops of water form on certain plants. surface tension pulls water into the simplest

shape – a perfect sphere – a shape of least surface area/volume ratio.

This same surface tension pulls water up thin tubes. This is called capillary action and plants use it to help them transport liquids up and down the stem.

2LookThe shap

2Usually it is not possible to make a film of water as the surface tension is too great so it rips the film apart. However, if we add detergent to water it can decrease surface tension by tenfold. It’s still there though.

U ally it is not possible to make a film of water he surface tension is too great so it rips the film

apart. However, if we add detergent to water it can decrease surface tension by tenfold. It’s still there though.

3 Usuaas thapart

3

Try this experiment:

Twist a piece of single strand wire to make a 1. large loop about 8cm in diameter.

Make a smaller loop of cotton.2.

Dip both into a water/detergent mix. Make sure 3. it is not too foamy! The wire loop should form a film.

Break the film inside the cotton loop using a pin 4. and see what happens!

T this experiment:

Twist a piece of single strand wire to make a 1.large loop about 8cm in diameter.

Make a smaller loop of cotton.2.

Dip both into a water/detergent mix. Make sure 3.it is not too foamy! The wire loop should form a film.

Break the film inside the cotton loop using a pin 4.and see what happens!

4Try t

4

Surface tension is caused by the fact that molecules of gas near the surface of a liquid do not attract the liquid molecules at the surface as much as other liquid molecules.

Molecule at surface Molecule within liquid Overall a pull inwards Overall no pull – it cancels out

S face tension is caused by the fact that molecules of gas near the surface of a liquid do not attract the liquid ecules at the surface as much as other liquid molecules.

Molecule at surface Molecule within liquid Overall a pull inwards Overall no pull – it cancels out

1Surfamole1



EXP 36What is a Wave?

Ask the class for ideas - spend a quick 5 minutes brainstorming then move on.

Don’t say what’s right or wrong, but repeat all ideas to the class so everyone can hear and spark ideas off each other.

Ignore anyone’s answers if they haven’t waited with their hand up to ask.

A k the class for ideas - spend a quick 5 minutes nstorming then move on.

Don’t say what’s right or wrong, but repeat all ideas to the class so everyone can hear and spark ideas off each other.

Ignore anyone’s answers if they haven’t waited with their hand up to ask.

1Ask brain1

How fast is that Mexican Wave travelling?

v = x t

(or if you haven’t done this ask how many meters per second the wave is doing).

Wave velocity = 500m = 25ms-1 20s

About 50mph (cheetah type speeds)

Look, maximum human velocity is about 25mph.

H w fast is that Mexican Wave travelling?

v = x t

(or if you haven’t done this ask how many meeters per second the wave is doing).

Wave velocity = 500m = 25ms-1 20s

About 50mph (cheetah type speeds)

Look, maximum human velocity is about 25mmph.

6How

v

What’s the world record for 100m? 9.8s. So the average speed of a 100m runner is about 10ms-1, 20mph. Note max is probably 12-13ms-1 i.e. 24-25 mph.

Note ms-1 to mph conversion is about x2

USEFUL!

What’s the world record for 100m? 9.8s. So the age speed of a 100m runner is about 10ms-1,

20mph. Note max is probably 12-13ms-1 i.e. 24-25 mph.

Note ms-1 to mph conversion is about x2

USEFUL!

4Whaavera20mp

4

Try the Mexican wave – you will need: 1m ruler, stop clock, tape measure.

The wave goes from Student 1 (e.g. Fred) to Student 2 (e.g. Lizzie). Get Fred to stand up and lift his hands quickly, and then sit down. When the student next to Fred sees him do it, he must do the same. Keep going until you get to Lizzie!

T the Mexican wave – you will need: 1m ruler, clock, tape measure.

The wave goes from Student 1 (e.g. Fred) to Student 2 (e.g. Lizzie). Get Fred to stand up and lift his hands quickly, and then sit down. When the student next to Fred sees him do it, he must do the same. Keep going until you get to Lizzie!

2Try tstop 2

So, what is the speed of a Mexican wave?

Get the class to close their eyes. “I want you to imagine a football stadium which is probably = 500m round (I know it depends on how high you are in the stands but run with me on this). Everyone put your hands up. When I say so imagine the start of the Mexican Wave. Imagine it going round the stadium. When it gets back to where it started put your hands down. I’m going to time how long you reckon it takes to get round.”

Now here everyone will have a different opinion but go for an average. It’s quite likely you’ll get times of between 10-30s. Go for the average say 20s.

S what is the speed of a Mexican wave?

the class to close their eyes. “I want you to imagine a football stadium which is probably = 500m round (I know it depends on how high you are in the stands but run with me on this). Everyone put your hands up. When I say so imagine the start of the Mexican Wave. Imagine it going round the stadium. When it gets back to where it started put your hands down. I’m going to time how long you reckon it takes to get round.”

Now here everyone will have a different opinion but

6

go for an average. It’s quite likely you’ll get times of between 10-30s. Go for the average say 20s.

5So, w

Get t5

Does everyone end up on Lizzie? No! So what actually moves? In this case information, that the person next to you has stood up and then sat down.

A wave is a way of transferring information!

4D s everyone end up on Lizzie? No! So whhat

ally moves? In this case information, thaat the person next to you has stood up and then sat d down.

A wave is a way of transferring information!

3Doesactuaperso

3



EXP 37 Ringing a Bell

So the wave can transfer (transport) information and it can do it quickly - faster than we can run!

The wave speed is dependent on how fast we react to the person next to us. What if we had a load of fit, young, fast people to do it? Let the students try! Get a student to measure the distance the wave travels in the class, and get a student to time it.

Show on the board how fast it goes. It’s surpris-ingly quick.

S the wave can transfer (transport) information and n do it quickly - faster than we can run!

The wave speed is dependent on how fast we react to the person next to us. What if we had a load of fit, young, fast people to do it? Let the students try! Get a student to measure the distance the wave travels in the class, and get a student to time it.

Show on the board how fast it goes. It’s surpris-ingly quick.

7So thit can7

Conclusion:

Waves transfer energy or information.

It is the energy/information that travels not the medium.

Waves can travel quickly.

C clusion:

es transfer energy or information.

It is the energy/information that travels not the medium.

Waves can travel quickly.

2Conc

Wav2

Waves can transfer more than information.

Get the pupils to stand in a long corridor or just use the lab. Put a bell on the opposite side of the room, To ring that bell requires energy. “I want to ring that bell without moving from this spot. How can I do it?” Give the students a clue by getting the big spring out.

Some bright spark might say, “tell a pupil” to do it. YES, this is good although not what is intended for the demo. (It’s good because your voice produces a sound wave, which travels through the air transfer-ring information to the pupil’s ear. Information is transferred by waves.)

W es can transfer more than information.

the pupils to stand in a long corridor or just use the lab. Put a bell on the opposite side of the room, To ring that bell requires energy. “I want to ring that bell without moving from this spot. How can I do it?” Give the students a clue by getting the big spring out.

Some bright spark might say, “tell a pupil” to do it. YES, this is good although not what is intended for the demo. (It’s good because your voice produces a sound wave, which travels through the air transfer-ring information to the pupil’s ear. Information is transferred by waves.)

8Wav

Get t8

By flicking the spring from far away the KE from the teacher’s hand travels up the spring by PE, and when it gets to the other side it flicks the bell. The bell converts the elastic energy to sound energy. The spring has transported energy from the teacher to the bell. The thing the wave travels through is called the medium. In this case the medium is the spring. Does the spring all end up at the far end? No! It’s the energy wave that travels and not the medium.

2B flicking the spring from far away the KE from

eacher’s hand travels up the spring by PE, and when it gets to the other side it flicks the bell. The bell converts the elastic energy to sound energy. The spring has transported energy from the teacher to the bell. The thing the wave travels through is called the medium. In this case the medium is the spring. Does the spring all end up at the far end? No! It’s the energy wave that travels and not the medium.

1By flthe tewhen

1

wiggle

long spring

bell

ding!!



EXP 38Categories of Wave

There are two ways to get a wave to travel up this long spring. Any ideas as to what the two ways are? Take ideas from the students.

As before, if the wiggle / disturbance /displacement is perpendicular/at right angles to the direction of wave travel/propagation. This is called a transverse wave.

If the wiggle/flick is in line with the direction of wave travel. This is called a longitudinal wave.

Th re are two ways to get a wave to travel up this long spring. Any ideas as to what the two ways are? Take s from the students.

As before, if the wiggle / disturbance /displacement is perpendicular/at right angles to the direction of wave travel/propagation. This is called a transverse wave.

If the wiggle/flick is in line with the direction of wave travel. This is called a longitudinal wave.

1Ther ideas 1

Now it’s quite difficult to see a longitudinal wave, but try making one with a slinky. Shove a stiff piece of A4 card in the slinky then make some waves and listen.N w it’s quite difficult to see a longitudinal wave, but try making one with a slinky. Shove a stiff piece of A4

in the slinky then make some waves and listen.2Now card 2

Most waves, such as light, radio, waves in the sea, etc, are transverse waves but a few very important ones e.g. sound, are longitudinal. Sound waves move by squashing and stretching (called compressions and rarefactions) the spaces between molecules. Note that molecules themselves don’t get stretched or squashed.

All waves of the electromagnetic spectrum are transverse e.g. light, radio and X-ray to mention but a few. For the EM spectrum an electromagnetic field is moving which strangely can move through nothingness, i.e. they can move through space.

Let’s look more at how light and sound behave.

M t waves, such as light, radio, waves in the sea, etc, are transverse waves but a few very important ones e.g. nd, are longitudinal. Sound waves move by squashing and stretching (called compressions and rarefactions)

the spaces between molecules. Note that molecules themselves don’t get stretched or squashed.

All waves of the electromagnetic spectrum are transverse e.g. light, radio and X-ray to mention but a few. For the EM spectrum an electromagnetic field is moving which strangely can move through nothingness, i.e. they can move through space.

Let’s look more at how light and sound behave.

3Mostsounthe s

3

wiggle/flick

direction of travel

Longitudinal Wave

wiggle/flick

long helix

direction of travel

Transverse Wave

Sci-fi type laser gun noises - brilliant!

card



EXP 39 The Speed of Sound

For this experiment you will need: a hammer, retort stand base, tape measure, 25 stop clocks and a student to record results.F this experiment you will need: a hammer, retort stand base, tape measure, 25 stop clocks and a student to

rd results.1For trecor1

The good news here is that you can just about trust a good student with a hammer and retort stand base, so you can be at the timing end with all the pupils to organise them. This is more likely to lead to success.Th good news here is that you can just about trust a good student with a hammer and retort stand base, so you

be at the timing end with all the pupils to organise them. This is more likely to lead to success.3 The can b3

2

Raise hand = Ready

Drop hammer = Go

Be careful not to hit the retort stand

Agree on this before

the student sets off!

base too hard!

Raise hand = Also ready

See drop hammer = Start timing

Hear hammer = Stop timing

22

Raise hand = Ready

Drop hammer = Go

Be careful not to hit the retort stand

Agree on this before

the student sets off!

base too hard!

Raise hand = Also ready

See drop hammer = Start timing

Hear hammer = Stop timing

Pupils walk/rotate/walk/rotate with metre rule to measure out total distance



EXP 40The Speed of Sound 2

For this experiment you need all the equipment that you used in EXP 39, plus a large wall.F this experiment you need all the equipment that

used in EXP 39, plus a large wall.1For tyou u1

Total distance = 10 x 200m

= 2000m

Total time ≈ 5s

Speed of sound :

2000m = 400ms-1 5s

TTotal l didistance = 1010 x 2 20000m

= 2000m

Total time ≈ 5s

Speed of sound :

2000m = 400ms-1 5s

4T

4

Hit it once and wait for the echo. Use this to get into a rhythm so you hit it as the echo returns. By doing this you can measure the time it takes to go there and back 10 times. Remember though, count 0 to 10 to get 10 travels, starting on the 0 and end-ing on the 10. 1 to 10 only travels 9 times.

Note: Depends on air pressure because this deter-mines how close the air molecules are.

4Hit it once and wait for the echo. Use this to get

a rhythm so you hit it as the echo returns. By g this you can measure the time it takes to go

there and back 10 times. Remember though, count 0 to 10 to get 10 travels, starting on the 0 and end-ing on the 10. 1 to 10 only travels 9 times.

Note: Depends on air pressure because this deter-mines how close the air molecules are.

3Hit itinto doing th

3

This time the sound wave travels there and back. Everyone can see easily when the hammer hits and it’s much easier to start clocks together. The wave travels double the distance to the wall, in this case 200m.

Thi time the sound wave travels there and back. ryone can see easily when the hammer hits and

it s much easier to start clocks together. The wave travels double the distance to the wall, in this case 200m.

2This Everit’s m

2

all pupils + you

retort stand base

wall

100m

100m



EXP 41 The Range of Hearing

Sound exists at all sorts of frequencies, but hu-mans can only hear some of them (20Hz – 20kHz). Sound that is higher than 20kHz cannot be heard by humans at all, and is called ultrasound. Sound lower than 20Hz also cannot be heard, and it is called infrasound.

S nd exists at all sorts of frequencies, but hu-s can only hear some of them (20Hz – 20kHz).

Sound that is higher than 20kHz cannot be heard zby humans at all, and is called ultrasound. Sound lower than 20Hz also cannot be heard, and it is called infrasound.

1SounmansSoun

1Bats and some birds use ultrasound. Bats use it to hunt by screeching in ultrasound. If there are moths nearby the ultrasound will bounce off them and come back to the bat’s ear, then the bat knows where they are.

B t and some birds use ultrasound. Bats use it unt by screeching in ultrasound. If there are

moths nearby the ultrasound will bounce off them and come back to the bat’s ear, then the bat knows where they are.

2Bats to humoth

2

Moths have a special kind of “ear”, which has a simple structure so the moth can tell when a bat uses ultrasound. The moth quickly flies in a differ-ent direction to try to get away from the bat.

M ths have a special kind of “ear”, which has a ple structure so the moth can tell when a bat

uses ultrasound. The moth quickly flies in a differ-ent direction to try to get away from the bat.

3Mothsimpuses

3Scans for unborn babies use ultrasound, as X-rays are too dangerous to sensitive multiplying cells in the foetus. All the men see the umbilical cord in the scan and mistakenly say ‘that’s my boy’.

S ns for unborn babies use ultrasound, as X-rays oo dangerous to sensitive multiplying cells in

the foetus. All the men see the umbilical cord in the scan and mistakenly say ‘that’s my boy’.

4Scanare tothe f

4

Elephants use infrasound.

Sometimes a family of elephants will suddenly stop moving and turn one way when we hear nothing. They are communicating at frequencies below 20Hzthat we cannot hear. Scientists recorded a female elephant going through her oestrus cycle and played it to some male elephants a few kilometres away with interesting results.

El hants use infrasound.

metimes a family of elephants will suddenly stop moving and turn one way when we hear nothing. They are communicating at frequencies below 20Hzthat we cannot hear. Scientists recorded a female elephant going through her oestrus cycle and played it to some male elephants a few kilometres away with interesting results.

5Elep

Som5

Dolphins also use sound to communicate. They can use that bulbous head (the organ inside is called a ‘melon’) to focus the sound, a bit like burning things with a magnifying glass. Some scientists believe they can use this to stun fish with sound.

D lphins also use sound to communicate. They use that bulbous head (the organ inside is called

a melon’) to focus the sound, a bit like burning things with a magnifying glass. Some scientists believe they can use this to stun fish with sound.

7Dolpcan ua ‘m

7Whales use a huge range of sound including infra-sound to communicate over long distances.Whales use a huge range of sound including infra-

nd to communicate over long distances.6Whasoun 6



EXP 42Record Player

You don’t need a fancy record player to play a song – you can make a paper record player!

For this experiment you will need a record, a base, a sharp pin, paper, sticky tape and Blu Tack.

Y don’t need a fancy record player to play a song u can make a paper record player!

For this experiment you will need a record, a base, a sharp pin, paper, sticky tape and Blu Tack.

1You – you 1

The records are attached to a cotton reel which can turn freely on a metal spoke which is attached to a wooden base. When you try to play your record make sure the base is held firmly so the record does not slip!

Th records are attached to a cotton reel which can freely on a metal spoke which is attached to

a wooden base. When you try to play your record make sure the base is held firmly so the record does not slip!

2The turn a wo

2

Make your paper cone out of a very large sheet of paper using the sticky tape to tape it closed. Tape a pin pointy side out on the thin side of the cone. Use the sharpest pin you can find! Next, weigh down your cone by sticking a lump of Blu Tack near the pin on the inside.

M ke your paper cone out of a very large sheet of er using the sticky tape to tape it closed. Tape a

pin pointy side out on the thin side of the cone. Use the sharpest pin you can find! Next, weigh down your cone by sticking a lump of Blu Tack near the pin on the inside.

3Makpape pin p

3Hold the cone lightly at the wide end and lay the pin gently into the groove of the record. Angle the pin about 45° to the horizontal, and make sure the pin is running straight in the groove. Turn the record with your finger. These records are 45rpm, which means they must turn 45 times every minute. Try asking your students to work out how long one full turn should take (Answer: 1.3s).

H ld the cone lightly at the wide end and lay the pin ly into the groove of the record. Angle the pin

about 45° to the horizontal, and make sure the pin is °running straight in the groove. Turn the record with your finger. These records are 45rpm, which means they must turn 45 times every minute. Try asking your students to work out how long one full turn should take (Answer: 1.3s).

4Holdgentlabou

4

Enjoy the music!E joy the music!5

Enjo 5

Any ray travellingparallel to theprincipal axis on the way to the lens/mirror will pass through the focal point on refraction/reflection.

A ray travellingllel to the

principal axis on the way to the lens/mirror will pass through the focal point on refraction/reflection.

4Any paralprinc

4



EXP 43 Rules for Ray Diagrams (Real Images)

When we do experiments with light waves it is useful to draw diagrams of what the light rays are doing. These are called ray diagrams. How do we do this? Let’s look at some rules about drawing ray diagrams:

When we do experiments with t waves it is useful to draw

diagrams of what the light rays are doing. These are called ray diagrams. How do we do this? Let’s look at some rules about drawing ray diagrams:

1Whelight diagr

1The Principal Axis.

The principal axis goes through the middle of the lens or mirror.

Th Principal Axis.

principal axis goes through the middle of the lens or mirror.

2The P

The p2

The Focal Point

This is where the lens or mirror focuses light from a distant (parallel rays) object.

Th Focal t

This is where the lens or mirror focuses light from a distant (parallel rays) object.

3The FPoin3

Any ray passing through the focal point on the way to the lens/mirror will travel parallel to the principal axis upon refraction/reflection.

A ray passing ugh the focal

point on the way to the lens/mirrorr will travel parallel to the principal axis upon refraction/reflection.

5Any throupoint

5

So by combining rays 1, 2 and 3 we can see that the image will look like this. The image forms where rays from one point of the object come back together.

S by combining rays 1, 2 and 3 we can see that mage will look like this. The image forms

where rays from one point of the object come back together.

7So by the imwher

7

Any ray that passes through or reflects from the centre of the lens/mirror will carry on in the same direction or reflect back along the same line.

A ray that es through or

reflects from the centre of the lens/mirror will carry on in the same direction or reflect back along the same line.

6Any passerefle

6



EXP 44Rules for Ray Diagrams (Virtual Images)

The rules for ray diagrams here are almost exactly the same. However, the rays will diverge (spread out) rather than converge, so they ‘appear’ to come from an imagined spot.

Th rules for ray diagrams here are almost exactly ame. However, the rays will diverge (spread

out) rather than converge, so they ‘appear’ to come f i i d tfrom an imagined spot.

1The rthe sout)

1Any ray travelling parallel to the principal axis on the way to the lens / mirror will appear to have come from the focal point on refraction reflection.

A ray travelling parallel to the principal axis he way to the lens / mirror will appear to have

come from the focal point on refraction reflection.p2

Any on thcome

2

Any ray passing through the focal point on the way to the lens/mirror will travel parallel to the principal axis upon refraction/reflection.

A ray passing through the focal point on the way e lens/mirror will travel parallel to the principal

axis upon refraction/reflection.p3

Any to thaxis

3Any ray that passes through or reflects from the centre of the lens/mirror will carry on in the same direction or reflect back along the same line.

A ray that passes through or reflects from the re of the lens/mirror will carry on in the same

direction or reflect back along the same line.4

Any centrdirec

4

Again, by combining the three rules we get the diagram.A in, by combining the three rules we get the

ram.5Agaidiagrg5

A convex mirror is the same. Have a look at the back of a spoon!A onvex mirror is the same. Have a look at the

k of a spoon!k of a spoon!6A coback back6



EXP 45 Reflection

Just like a ball bouncing off a wall, waves reflect off things. If we want to see how reflec-tion works, we can pick a wave we can see, like light!

J t like a ball ncing off

a wall, waves reflect off things. If we want to see how reflec-tion works, we can pick a wave we can see, like light!

1Just bouna wa

1

Satellite receiver dishes are parabolas. The receiver is placed in front of the parabola, at the focus point.

S t llite receiver dishes are bolas. The receiver is placed

in front of the parabola, at the focus point.

7Satelparabin fro

7

Try this demonstration:

Ask pupils to find a relationship between the incoming ray (i) (incident) and the reflected ray (r). They should find that

r = i.

Not that exciting in itself but it has some exciting consequences.

T this demonstration:

pupils to find a relationship betwween the incoming ray (i) (incident) and th he reflected ray (r). They should find thhat

r = i.

Not that exciting in itself but it has s some exciting consequences.

2Try t

Ask 2

Parabolic reflectors can be used to gather energy from a large area and focus it all onto one point.

PP bbolilic reflfle tctors can bbe used d tto g tathher gy from a large area and focus it all

onto one point.6

Parabenergonto

6

Think if we had a lot of small mirrors. All the rays focus on one point.

Ask if anyone recognises this shape yet.

Think if we had a lot of small mirrors. All the rays s on one point.

Ask if anyone recognises this shape yet.

4Thin focu 4

ri

Now try this demonstration (it’s probably best as a demo unless you have lots of mirrors):

Adjust the three ray boxes so they all three rays converge (focus) onto one point.

4N w try this demonstration (it’s probably best as a

o unless you have lots of mirrors):

Adjust the three ray boxes so they all three rays Adjust the three ray boxes so they all three rays converge (focus) onto one point.

3Now demo3

r

rr

i

i

lightbox

ri

mirror

Lots of mirrors approximate a rounded surface - it’s a parabolic reflector!

L t of mirrors approximate a ded surface - it’s a

parabolic reflector!5

Lots rounparab

5

r

i

parallel beams/rays

in

all rays focussed on one pointparabolic reflector



EXP 46Making a Periscope

Here’s a lovely example of r = i. It is used in sub-marines and at horse races – it’s a periscope!Here’s a lovely example of r = i. It is used in sub-

nes and at horse races – it’s a periscope!1Heremari1

A useful box to use for making your periscope is a tall juice box, but you can always make your own box too.

A eful box to use for making your periscope is a uice box, but you can always make your own

box too.2

A ustall jbox t

2

Make your periscope like this:M ke your periscope like this:3

Mak3

This is what your periscope should look like from the outside:

Light comes in through the hole in the top and out at the bottom (other side!).

Thi is what your periscope should look like from outside:

Light comes in through the hole in the top and out at the bottom (other side!).

4This the o4

Use your periscope to see over tall things. If you are short, use it to peek over the tall pupils’heads!U your periscope to see over tall things. If you are short, use it to peek over the tall pupils’heads!5

Use 5



EXP 47 Reflection (Continued)

Does reflection depend on wavelength (is it affected by wavelength)?

Repeat the demonstration with the mirrors but this time place them on an A3 piece of paper and put different colour filters in front of the ray boxes. First 3 blue, then 3 green, then 3 red. Mark on the paper where the focus point is each time.

The focus point should not change. Reflection an-gles are not affected by wavelength (colour). This is important.

D s reflection depend on wavelength (is it affected wavelength)?

Repeat the demonstration with the mirrors but this time place them on an A3 piece of paper and put different colour filters in front of the ray boxes. First 3 blue, then 3 green, then 3 red. Mark on the paper where the focus point is each time.

The focus point should not change. Reflection an-gles are not affected by wavelength (colour). This is important.

1Doesby w1

So we have something that can focus light and focused all colours on the same point. We’ll come back to why this is so important after refraction.

S we have something that can focus light and sed all colours on the same point. We’ll come

back to why this is so important after refraction.2

So wfocuback

2

Parabolic reflectors are used to pick up the tiny signals from satellites out in space and focus the energy on one point where the receiver is.

P bolic reflectors are used to pick up the tiny als from satellites out in space and focus the

energy on one point where the receiver is.3

Parabsignaenerg

3

When ornithologists want to record bird song they use a parabolic reflector to focus the sound, a weak sound can be picked up a long distance away.

When ornithologists want to record bird song they a parabolic reflector to focus the sound, a weak

sound can be picked up a long distance away. 4

Wheuse a soun

4

Watch a cat’s ears; they use parabolic reflectors to focus the sound down their auditory canal.W tch a cat’s ears; they use parabolic reflectors to

s the sound down their auditory canal.5Watcfocu 5

Demo: Get the class to have parabolic reflectors for ears. Cup your hands behind your ears to parabolic reflect the sound. Now make a loud ‘BUP’ sound. Great!

Cup your hand round the back of your ear, then pull your ear forward.

D mo: Get the class to have parabolic reflectors for Cup your hands behind your ears to parabolic

reflect the sound. Now make a loud ‘BUP’ sound. Great!

Cup your hand round the back of your ear, then pull your ear forward.

6Demears. reflec

6

coloured filter



EXP 48Images in a Plane Mirror

Here the pupils see the lighted candle superimposed on the unlit one and as you fill the beaker with water the flame continues to burn. Candles must be iden-tical and wicks lined up.

H e the pupils see the lighted candle superimposed he unlit one and as you fill the beaker with water

the flame continues to burn. Candles must be iden-tical and wicks lined up.

4Hereon ththe fl

4

Tell pupils to look out for writing on the front of ambulances. Why are they the wrong way round?T ll pupils to look out for writing on the front of

ulances. Why are they the wrong way round?6Tell pambu6

Remind pupils that angle of incidence (incoming angle) i, equals angle of reflection r. i = r.

R mind pupils that angle of incidence (incoming e) i, equals angle of reflection r. i = r.1

Remangle1

Try getting a small coin. Place one coin between you and the mirror. Then by looking in the mirror and then past it try to put the other coin where the image of the first is.

You should find that the coins are equal distance from the mirror.

T getting a small coin. Place one coin between and the mirror. Then by looking in the mirror

and then past it try to put the other coin where the image of the first is.

You should find that the coins are equal distance from the mirror.

2Try gyou aand t

2

normal line

r

i

place this coin where image of A is

AB

Your mind believes light to travel in straight lines so your eye ‘sees’ the image at B. It’s a virtual image, since light doesn’t actually come from there.Y r mind believes light to travel in straight lines so your eye ‘sees’ the image at B. It’s a virtual image, since

t doesn’t actually come from there.

r

r i

i

AB

5Yourlight 5

Try this experiment – burning a candle underwater.

4

6

T this experiment – burning a candle underwater.3

Try t3

pane of glass (you need to adjust this)

lit candle unlit candle

a b



EXP 49 Refraction

Refraction or bending of waves occurs because of a change in speed. It’s easiest to see this with light waves but it occurs in all types of waves.

R f action or bending of waves occurs because of ange in speed. It’s easiest to see this with light

waves but it occurs in all types of waves.1

Refraa chawave

1What causes the bending, why does a change of speed cause a change in direction?What causes the bending, why does a change of

d cause a change in direction?2Whaspee 2

Note the ‘normal’ line is a line that is at right angles to the boundary between glass and air (or any boundary).

N te the ‘normal’ line is a line that is at right angles e boundary between glass and air (or any

boundary).5

Noteto thboun

5Experiment:

Try looking at someone’s eyes through a glass block as they twist it from side to side. The eyes look as if they are moving around the head!

E eriment:

y looking at someone’s eyes through a glass block as they twist it from side to side. The eyes look as if they are moving around the head!

7Expe

Try l7

Experiment:

Place a pencil in a beaker half full of water. Move the pencil from side to side.

E eriment:

e a pencil in a beaker half full of water. Move the pencil from side to side.

6Expe

Place 6

Look at this line of people walking side by side on concrete. On concrete they can walk quickly but when they get to the mud they slow down. The change in speed causes a change in direction.

L k at this line of people walking side by side on crete. On concrete they can walk quickly but

when they get to the mud they slow down. The change in speed causes a change in direction.

3Lookconcwhen

3

concrete

mud

Light travels more slowly through glass and water than through air.Li ht travels more slowly through glass and water

through air.4Ligh than 4

AIR

AIR

GLASS

light bends away from the

normal line

light bends away from the

normal line



EXP 50Refraction (Continued)

Experiment: Looking at lenses

Try different lenses here. Ask pupils what deter-mines how much the light is bent by the lens. It’s not the thickness of the lens but the curvature.

E eriment: Looking at lenses

y different lenses here. Ask pupils what deter-mines how much the light is bent by the lens. It’s not the thickness of the lens but the curvature.

4Expe

Try d4

Experiment: Combining a few refractions.

Look, the light has got nearer.

E eriment: Combining a few refractions.

Look, the light has got nearer.

2Expe

2

It’s the curvature that matters, not the thickness.

Weak lens Strong lens

ItIt’’ t thhe curvatture t thhat t matttters, n tot t thhe kness.

Weak lens Strong lens

5It’s tthick5

Experiment: What effect does angle have on the amount of bending?

The greater the angle the more the light gets bent.

E eriment: What effect does angle have on the amount of bending?

The greater the angle the more the light gets bent.

1Expe

1LIGHT

This is starting to look a bit like a lens!

This pattern is slightly different (it’s converging) as the boundary going into the glass is not parallel to the boundary coming out of the glass.

Thi is starting to look a bit like a lens!

s pattern is slightly different (it’s converging) as the boundary going into the glass is not parallel to the boundary coming out of the glass.

3This

This 3

Looking at near things:

Near light is very diverging. The curved (fat) lens bends the diverging incoming light, which needs lots of bending to get it to focus.

L king at near things:

r light is very diverging. The curved (fat) lens bends the diverging incoming light, which needs lots of bending to get it to focus.



EXP 51 Lenses in Eyes and Cameras

Most of the lensing done by the eye is done by the cornea (front surface of the eye), and the lens only does the fine adjustment for near or far.

M t of the lensing done by the eye is done by the ea (front surface of the eye), and the lens only

does the fine adjustment for near or far.1

Mostcornedoes

1Light is focussed onto the retina (the light detec-tors). All the information detected by the retina is then sent to the brain through the optic nerve. Where this enters the retina there are no receptors, so you have a blind spot.

Li ht is focussed onto the retina (the light detec-. All the information detected by the retina

is then sent to the brain through the optic nerve. Where this enters the retina there are no receptors, so you have a blind spot.

2Ligh tors)is the

2

Get the students to experience their blind spot. There is a page for this at the back of the book, but it works on any blank paper, just draw two spots 10cm horizontally apart. Cover your right eye and look just at the spot on the right holding the paper about an A4 length away from your face.

G t the students to experience their blind spot. re is a page for this at the back of the book, but

it works on any blank paper, just draw two spots 10cm horizontally apart. Cover your right eye and look just at the spot on the right holding the paper about an A4 length away from your face.

3Get tTher it wo

3

4Look

Near4

We can demonstrate how the eye looks at near and far things by trying EXP 52, the Fluorescein Eye.W can demonstrate how the eye looks at near and

hings by trying EXP 52, the Fluorescein Eye.6We cfar th6

Looking at far things:

Far light is nearly parallel. The muscles controlling the lens make the lens thin. the parallel light does not need much bending to get it to focus.

L king at far things:

Far light is nearly parallel. The muscles controlling the lens make the lens thin. the parallel light does not need much bending to get it to focus.

5Look

5



EXP 52The Fluoroscein Eye

Move the angle poise near or far from the ‘eye’ and see it focused or not as the beam becomes more or less parallel.

This eye can also be used to show long or short sight corrections.

M ve the angle poise near or far from the ‘eye’ and t focused or not as the beam becomes more or

less parallel.

This eye can also be used to show long or short sight corrections.

2Movsee iless p

Short-sighted:Sh rt-sighted:3

Shor3

Long-sighted:L g-sighted:5

Long5

Glasses for long-sighted people:

Correct with a converging lens

Gl ses for long-sighted people:

Correct with a converging lens

6Glas

6

Glasses for short-sighted people:

Correct with a diverging lens

Gl ses for short-sighted people:

Correct with a diverging lens

4Glas

The fluorescein makes the light inside the eye show. Instead of fluorescein you can also use diluted milk. 2

4

Th fluorescein makes the light inside the eye show. ead of fluorescein you can also use diluted milk.

light focussed here

converging lens stuck to flask with blu tack

bright beam of light from angle poise lamp

spherical flask with water and fluoroscein

cornea/lens is not strong enough

light is focussed past the retina

cornea/lens is too strong

light is focussed short of the retina

1The flInste1



EXP 53 The Pinhole Camera

The pinhole camera is great, as it gives you an ‘im-age’ of sorts without the need for a lens.

However, to see it you need to have a dark lab, as the amount of light coming through that small hole is only tiny.

Th pinhole camera is great, as it gives you an ‘im- of sorts without the need for a lens.

However, to see it you need to have a dark lab, as the amount of light coming through that small hole is only tiny.

1The page’ 1

You can get visible images in a lighter lab if you have very bright objects to look at e.g. angle poise lamp etc.

Y can get visible images in a lighter lab if you e very bright objects to look at e.g. angle poise

lamp etc.2

You havelamp

2

Toilet rolls are good for the body, black thick paper for the front, greaseproof paper for the back. You’ll need optic (big) pins to make the holes.

Remember, pins are sharp!

Elastic bands are useful.

Toilet rolls are good for the body, black thick k paper he front, greaseproof paper for the back. You’ll

need optic (big) pins to make the holes.

Remember, pins are sharp!

Elastic bands are useful.

4Toilefor thneed

The best thing to look at is a carbon filament lamp, as it shows the filament very nicely on the pinhole camera. However, these are quite specialist and you may not have one, so make do with what you’ve got.

4Th best thing to look at is a carbon filament lamp,

shows the filament very nicely on the pinhole camera. However, these are quite specialist and you may not have one, so make do with what you’ve got.

3The bas it came

3

Now you can use your pinhole camera!N w you can use your pinhole camera!6

Now 6

Now put together all the components like this:N w put together all the components like this:5

Now 5

greaseproof paper screen

elastic bands black paper with pinhole

toilet roll/white plastic tube

This gives a dim but sharp picture as only one ray from each point reaches the screen.

The lightbulb is throwing out lots of rays but only very few get through the pinhole.

Thi gives a dim but sharp picture as only ray from each point reaches the screen.

The lightbulb is throwing out lots of rays but only very few get through the pinhole.

7This one r7

picture appears here upside down



EXP 54The Pinhole Camera (Continued)

Explanation: Now we have 2 places that 2 single rays can get through so we get two dim but sharp images.

E lanation: Now we have 2 places that 2 single can get through so we get two dim but sharp

images.2

Explrays imag

2

Get the pupils to make more holes.

Lots of pin holes. It all starts to overlap with lots of pictures of the lamp. It gets difficult to make out one picture from another.

G t the pupils to make more holes.

s of pin holes. It all starts to overlap with lots of pictures of the lamp. It gets difficult to make out one picture from another.

3Get t

Lots 3

Get the pupils to make one big hole with their finger.G t the pupils to make one big hole with their

er.4Get tfinge4

How do you get all the images to focus back onto one point? Use a lens!

H w do you get all the images to focus back onto point? Use a lens!5

How one p5

Note: Lens focal length has to match approximately the length of the pinhole camera. Photosensitive paper can be used to take photographs.

N te: Lens focal length has to match approximately ength of the pinhole camera. Photosensitive

paper can be used to take photographs.7

Notethe lepape

7

Explanation:

Rays A and B, which would have formed two pic-tures in separate places are brought together, as are all the rays, to form a bright focused image.

E lanation:

ys A and B, which would have formed two pic-tures in separate places are brought together, as are all the rays, to form a bright focused image.

6Expl

Rays6

What happens if we introduce another pin hole? Get students to try it.

With 2 pinholes we get 2 pictures.

What happens if we introduce another pin hole? students to try it.

With 2 pinholes we get 2 pictures.

1WhaGet s1

bright blob of unfocused light made up of millions of images all overlapping

Turn the card and block round.

You will not be able to see the pin clearly, if at all.

T n the card and block round.

will not be able to see the pin clearly, if at all.3

Turn

You 3

For this experiment you will need a wooden block with a pin stuck on it and a card with a pinhole placed behind it.

Place the block up near to your eye. You should see an image of the pin upside down through the pinhole.

F this experiment you will need a wooden block with a pin stuck on it and a card with a pinhole placed behind

Place the block up near to your eye. You should see an image of the pin upside down through the pinhole.

2For tit.2



EXP 55 The Eye as a Pinhole Camera

This is a great demonstration, but be careful!

Don’t poke your eye when you are holding things close to it!

This is a great demonstration, but be careful!

’t poke your eye when you are holding things close to it!1

This

Don’1



EXP 56UFOs and Mirages

A combination of refraction and total internal reflec-tion can lead to some interesting phenomena.A mbination of refraction and total internal reflec-

can lead to some interesting phenomena.1A cotion 1

‘The City in the Sky.’ This has been seen by many travellers in certain weather conditions.‘The City in the Sky.’ This has been seen by many

ellers in certain weather conditions.2‘The trave2

This is a picture of the Mojave Desert in Nevada, U.S. It looks like there is a lake in the desert, but of course, it is just a mirage!

Thi is a picture of the Mojave Desert in Nevada, It looks like there is a lake in the desert, but of

course, it is just a mirage!4

This U.S. cour

city

light is refracted bit by bit through the different densities of air until total internal reflection occurs

people see a city in the sky

decr

easi

ng d

ensi

ty

ship

Imagine a car driving in the city with its headlights on. Two lights would be seen in the same way as a city in the sky. Could it be a UFO?

What if a car is driving over tarmac on a hot day? Here the hot tarmac causes different densities of air above the road. Light from the car is refracted and then totally internally reflected. The eye sees the car image coming from the road. The mind inter-prets it as a reflection from water on the road (same as water in a desert).

I gine a car driving in the city with its headlights Two lights would be seen in the same way as a

city in the sky. Could it be a UFO?

What if a car is driving over tarmac on a hot day?

4

Here the hot tarmac causes different densities of air above the road. Light from the car is refracted and then totally internally reflected. The eye sees the car image coming from the road. The mind inter-prets it as a reflection from water on the road (same as water in a desert).

3Imagon. Tcity i

3

refraction

lowdensity

highdensity

total internal reflection



EXP 57 Telescopes and Reflection/Refraction

Telescopes help us to see a long way away. Most telescopes are used to see things in space. Light has to get to the telescope from a very long way away, and telescopes have to be designed so that they col-lect the light in the right way to make a good image.

Get the pupils to imagine they are building their own telescope. Ask pupils which they would use and why: Reflection of refraction?

T l scopes help us to see a long way away. Most copes are used to see things in space. Light has

to get to the telescope from a very long way away, and telescopes have to be designed so that they col-lect the light in the right way to make a good image.

Get the pupils to imagine they are building their own telescope. Ask pupils which they would use and why: Reflection of refraction?

1Telestelesto ge

1Ask pupils who answer this question about why you can’t focus on red and blue at the same time?

The answer is that with a refracting focus (as with a lens) blue is focused at a different point to red because:

The amount of refraction (bending) is wavelength dependent.

A k pupils who answer this question about wwhy you t focus on red and blue at the same time?

The answer is that with a refracting focus (as with a lens) blue is focused at a different point to rred because:

The amount of refraction (bending) is wavelength dependent.

2Ask can’t 2

We can also focus using reflection using parabolic mirrors.

Reflection is not wavelength dependent.

W can also focus using reflection using paraabolic ors.

Reflection is not wavelength dependent.

3We cmirro3

What would happen if we looked at a star through a refracting telescope?

The image would appear blurred as the red is fo-cused at a different point to the blue.

What would happen if we looked at a star through a acting telescope?

The image would appear blurred as the red is fo-cused at a different point to the blue.

5Wharefra5

Interestingly, a squid’s eye also uses reflective focussing.I t restingly, a squid’s eye also uses reflective

ssing.7Interfocu7

So decent/large telescopes use parabolic reflectors/mirrors to focus the light to get a clear crisp image for all colours.

S decent/large telescopes use parabolic reflectors/ors to focus the light to get a clear crisp image

for all colours.6

So dmirrofor a

6

Light coming from a distant star is white of sorts… well, at least it consists of different wavelengths of colour.

Li ht coming from a distant star is white of sorts… , at least it consists of different wavelengths of

colour.

These telescopes are known as the Very Large Array.

They are in Socorro, New Mex-ico, United States.

These telescopes are known as the Very Large Array.

They are in Socorro, New Mex-ico, United States.

4Ligh well, colou

4



EXP 58Wavelength (λ) and Frequency (f)

Imagine a runner.

His step length is + 2.5m and he takes 2 steps a second.

What’s his speed? Many pupils will work this out intuitively.

2.5m a step → 5 meters per second2 steps a second

I gine a runner.

step length is + 2.5m and he takes 2 steps a second.

What’s his speed? Many pupils will work this out intuitively.

2.5m a step → 5 meters per second2 steps a second

1Imag

His s1

But how did you work it out? You multiplied.

Speed = steps per x step second length

B t how did you work it out? You multipliedd.

Speed = steps per x step second lengthx

2But h

S2

Wave = waves x wavelengthspeed per sec

Waves per second is frequency (f)

Wavelength is λ

Wave speed is c

so:

c = f λ

Wave = waves x wavelengthspeed per sec

Waves per second is frequency (f(f( )f)f

Wavelength is λ

Wave speed is c

so:

c = f λ

4Ws4

This means for higher wavelengths the frequency is lower and vice versa.

c = f x λ

300,000,000 = 30,000 x 10,000

= 300,000 x 1,000

= 3,000,000 x 100

Thi means for higher wavelengths the frequeency is er and vice versa.

c = f x λ

300,000,000 = 30,000 x 10,000

= 300,000 x 1,000

= 3,000,000 x 100

6This lowe6

In the electromagnetic spectrum wave speed (c) is a constant value of 300,000,000 ms-1.I the electromagnetic spectrum wave speed (c) is a

tant value of 300,000,000 ms-1.5In thcons5

The same happens in waves.

Imagine a wave:

There are 2 waves a second.

So, wave speed = 5 ms-1

Th same happens in waves.

gine a wave:

There are 2 waves a second.

So, wave speed = 5 ms-1

3The

Imag3

wavelength = 2.5m

step length



EXP 59 The Electromagnetic Spectrum

Many waves (apart from sound) are part of the electromagnetic spectrum. They all travel at the same speed: the speed of light.M y waves (apart from sound) are part of the electromagnetic spectrum. They all travel at the same speed: the

d of light.1Manspeed 1

Because they all travel at the same speed, as wave-length goes up the frequency goes down (see EXP 58)

B ause they all travel at the same speed, as wave-th goes up the frequency goes down (see EXP

58)2

Becalengt58)

2All EM wavelengths can travel through a vacuum, through nothingness, through space. Sound can’t do this.

All EM wavelengths can travel through a vacuum, ugh nothingness, through space. Sound can’t do

this.3

All Ethrouthis

3

What are EM waves used for?What are EM waves used for?4

Wha4

Radio waves

Bounce off the atmosphere so you can talk to yourself as the radio waves bounce back round the Earth, if you • have a powerful enough transmitter.

Radio is used to talk to satellites, and communication on space missions as well as radio stations on the • ground.

R dio waves

Bounce off the atmosphere so you can talk to yourself as the radio waves bounce back round the Earth, if you have a powerful enough transmitter.

Radio is used to talk to satellites, and communication on space missions as well as radio stations on the •ground.

5Radi

B•5

Microwaves

Mobile phones •

Microwave ovens to cook your food.•

Scientists detect microwave emissions from • space, used to support the Big Bang theory

Mi rowaves

Mobile phones

Microwave ovens to cook your food.•

Scientists detect microwave emissions from •space, used to support the Big Bang theory

6Micr

M•6

RADIO MICROWAVE IR VISIBLE UV X-RAY GAMMA RAY

Wavelength increasing

Frequency increasing

RADIO MICROWAVE IR VISIBLE UV X-RAY GAMMA RAY

Wavelength increasing

Frequency increasing



IR

to detect casualties under rubble – camera con-• verts IR to visible so we can see it

remote controls on TV•

night vision•

helps with muscle problems•

reconnaissance planes photograph airstrips • where ground is cooler where planes have been i.e. they leave an IR shadow.

IR

to detect casualties under rubble – camera con-verts IR to visible so we can see it

remote controls on TV•

night vision•

helps with muscle problems•

reconnaissance planes photograph airstrips •where ground is cooler where planes have been i.e. they leave an IR shadow.

7IR

t•7

Watch out! Some EM waves can be dangerous:

microwaves cook you

Infra Red (IR) burns you

UV gives you skin cancer and can damage your eyes

X rays can destroy or alter nuclei of cells

Watch out! Some EM waves can be dangerous:

owaves cook you

Infra Red (IR) burns you

UV gives you skin cancer and can damage your eyes

X rays can destroy or alter nuclei of cells

11Watch

micro11

UV

sun beds for tanning•

security pens•

detecting forged bank notes•

biological washing powders absorb UV (invis-• ible light) and retransmit it as visible light i.e. appearing to give out more light than it takes in – appearing ‘whiter than white’

UV

sun beds for tanning

security pens•

detecting forged bank notes•

biological washing powders absorb UV (invis-•ible light) and retransmit it as visible light i.e. appearing to give out more light than it takes in – appearing ‘whiter than white’

8UV

s•8

X rays

which go through soft tissue well, but not so • well through bone – lets you see into the body

given out by very hot objects e.g. stars collaps-• ing

X ys

which go through soft tissue well, but not so well through bone – lets you see into the body

given out by very hot objects e.g. stars collaps-•ing

9X ray

w•9

This dog has had its photo taken with an IR camera. You can see the hottest bits are the eyes and mouth, where the image is glowing yellow/white.

This dog has had its photo taken with an IR camera. You can see the hottest bits are the eyes and mouth, where the image is glowing yellow/white.

This is one of the first X-ray photo-graphs ever taken. It was made by the scientist Wilhelm Röntgen, of his wife’s hand. You can see the ring on her hand!

This is one of the first X-ray photo-graphs ever taken. It was made by the scientist Wilhelm Röntgen, of his wife’s hand. You can see the ring on her hand!

Gamma rays

treatment of cancer by killing cells if given a • high enough dose

sterilising food by killing off of bacteria•

G ma rays

reatment of cancer by killing cells if given a high enough dose

sterilising food by killing off of bacteria•

10Gamm

tr•10



EXP 60 Standing Waves

When you vibrate one end of the cord standing wave patterns begin to appear. Standing waves have parts where the cord moves a lot (antinodes) and parts where it does not move at all (nodes). Depending on how fast you vibrate it you can get different numbers of antinodes and nodes.

When you vibrate one end of the cord standing wave patterns begin to appear. ding waves have parts where the cord moves a lot (antinodes) and parts

where it does not move at all (nodes). Depending on how fast you vibrate it you can get different numbers of antinodes and nodes.

3WheStandwher

3

The standing wave pattern also depends on the tension of the cord. You can vary the tension by changing the number of masses you use. Try using differ-ent tensions and see how this affects the standing wave.

Th standing wave pattern also depends on the tension of the cord. You can the tension by changing the number of masses you use. Try using differ-

ent tensions and see how this affects the standing wave.4

The vary ent te

4

For this experiment you will need some white rubber cord, a pulley, some slotted masses and vibration equipment.F this experiment you will need some white rubber cord, a pulley, some slotted masses and vibration equipment., some slotted masses and vibration equipment.2

For t2

Standing waves are not strictly on the specification but they can lead to excellent discussions about wavelength/frequency/pitch and amplitude. They are also a lot of fun to watch!St ding waves are not strictly on the specification but they can lead to excellent discussions about wavelength/

uency/pitch and amplitude. They are also a lot of fun to watch!1Standfrequ1



EXP 61Standing Waves on a Guitar

Waves bounded by either end of the cord are mov-ing backwards and forwards to give the stationary pattern seen.

Stationary waves are very important in musical instruments.

W es bounded by either end of the cord are mov-backwards and forwards to give the stationary

pattern seen.

Stationary waves are very important in musical instruments.

1Waving bpatte

1

Try this experiment:

Get the fundamental wave on the equipment. • Kill the fundamental with your fingers by pinching the cord.

Get the next wave up on the equipment. This • time pinch the cord exactly in the middle of its length and show that the wave continues as it isn’t trying to move at this point anyway.

T this experiment:

Get the fundamental wave on the equipment. Kill the fundamental with your fingers by pinching the cord.

Get the next wave up on the equipment. This •time pinch the cord exactly in the middle of its length and show that the wave continues as it isn’t trying to move at this point anyway.

2Try t

G•2

Harmonics:

Get a guitar and pluck one string to get the funda-mental note.

Now place a finger gently on the string exactly half way between the bridge and neck. As you pluck the string remove the finger. Listen for a high bell-like note. This is called a harmonic note.

H monics:

a guitar and pluck one string to get the funda-mental note.

Now place a finger gently on the string exactly half way between the bridge and neck. As you pluck the string remove the finger. Listen for a high bell-like note. This is called a harmonic note.

3Harm

Get a 3

pinch herepinch herepinch here



EXP 62 Straw Flutes

This next bit is great fun, but only suitable at the end of the lesson. Once the kids make straw flutes there’s no peace!

Thi next bit is great fun, but only suitable at the of the lesson. Once the kids make straw flutes

there’s no peace!1

This end othere

1This is an example of standing waves down a tube. It’s the same principle as the rubber cord with the waves produced by a reed and bounded by the tube of the straw.

Thi is an example of standing waves down a tube. the same principle as the rubber cord with the

waves produced by a reed and bounded by the tube of the straw.

2This It’s twave

2

To get different notes try cutting the tube shorter, so reducing wavelength and increasing frequency.

Use blunt scissors for this and be careful not to cut yourself!

To get different notes try cutting the tube shorrter, so cing wavelength and increasing frequenccy.

Use blunt scissors for this and be careful not to cut yourself!

5To gredu5

To make straw flutes all you need are some plastic straws and some scissors.

Use the scissors to cut the edges off one end of the straw in a V-shape. Flatten the V with your fingers.

Put the V in your mouth and try to blow it so that it vibrates.

T make straw flutes all you need are some plastic ws and some scissors.

Use the scissors to cut the edges off one end of the straw in a V-shape. Flatten the V with your fingers.

Put the V in your mouth and try to blow it so that it vibrates.

3To mstraw3

Next, try cutting holes in the tube. The wave is bounded by the nearest openhole to the reed. So by covering more holes wavelength increases and frequency/pitch drops.

N t, try cutting holes in the tube. The wave is nded by the nearest openhole to the reed. So

by covering more holes wavelength increases and frequency/pitch drops.

4Nextbounby co

4

An elephant trunk is a fixed length so it can only ‘trumpet’ certain waves.A elephant trunk is a fixed length so it can only

mpet’ certain waves.6An e‘trum6

1.5cm approx.

plastic straw

Blow like a sax. Try different tighnesses with your lips.

flatten the reed with fingers

cut as V shapes



EXP 63Making Music

For a straw of 10cm (0.1m)

λ = 4 x 0.1 = 0.4

speed of sound in air = 330ms-1

Frequency = c λ

= 330 0.4

=825Hz

F a straw of 10cm (0.1m)

λ = 4 x 0.1 = 0.4

speed of sound in air = 330ms-1

Frequency = c λ

= 330 0.4

=825Hz

5For a

λ 5

Remember our runner example from EXP 58? We learned the equation

c = f λ

We can use this equation to get the frequency from the length of the straw.

R member our runner example from EXP 58? We ned the equation

c = f λ

We can use this equation to get the frequency y from the length of the straw.

4Remlearn4

So the straw flute has a maximum wavelength that is 4 times the length of the straw. 4S the straw flute has a maximum wavelength that

times the length of the straw.3So this 4 t3

Use c = f λ to help you choose where to put your holes.U c = f λ to help you choose where to put your

s.7Use holes7

Middle C is 261.63Hz

This is around the frequency of B above middle C

Use this table to look up some frequencies.

Note Pitch/Freq Length

G 392.00

A 440.00

B 493.88

C 523.25

D 587.33

Middle C is 261.63Hz

is around the frequency of B above middle C

Use this table to look up some frequencies.

Note Pitch/Freq Length

G 392.00

A 440.00

B 493.88

C 523.25

D 587.33

6Midd

This 6

The wave inside a straw flute exists as a pressure wave and at the same time as a motion wave. This is a model clarinet (closed tube) not a flute (open tube), so its wave pattern is:

Th wave inside a straw flute exists as a pressure e and at the same time as a motion wave. This

is a model clarinet (closed tube) not a flute (open tube), so its wave pattern is:

1The wwaveis a m

1

pressure

Look one wave folded back on itself.L k one wave folded back on itself.2

Look2

½λ

¼λ



EXP 64 Elephants and Tubes

Ever heard an elephant trumpet? Listen closely, only certain notes are heard, they go up in steps not in a continuous way. Why are only certain notes possible?

E r heard an elephant trumpet? Listen closely, certain notes are heard, they go up in steps not

in a continuous way. Why are only certain notes possible?

1Ever only in a c

1As with the straw flute only certain waves will fit exactly into his/her trunk, so only certain frequen-cies of standing wave will be heard.

A with the straw flute only certain waves will fit ctly into his/her trunk, so only certain frequen-

cies of standing wave will be heard.2

As wexaccies

2

Demonstrate the whirling tube.

This is good with a hoover tube or similar. Tubes of around 0.8m are good, open both ends.

Swirl it slowly to get a low note and faster to get the harmonics. Note only certain frequencies are heard.It’d be difficult to get the fundamental but all higher harmonics starting from length of tube = λ are pos-sible.

D monstrate the whirling tube.

is good with a hoover tube or similar. Tubes of around 0.8m are good, open both ends.

Swirl it slowly to get a low note and faster to get the harmonics. Note only certain frequencies are heard.It’d be difficult to get the fundamental but all higher harmonics starting from length of tube = λ are pos-sible.

3Dem

This 3

The swirling pushes air down the tube. The cor-rugations (ridges on the tube) cause eddies (little currents of air) which vibrate the air. At certain frequencies the waves exactly fit into the length of the tube.

Th swirling pushes air down the tube. The cor-tions (ridges on the tube) cause eddies (little

currents of air) which vibrate the air. At certain frequencies the waves exactly fit into the length of the tube.

6The rugatcurre

6

This is just like the elephant’s trunk. Only certain frequencies/notes are possible.Thi is just like the elephant’s trunk. Only certain

uencies/notes are possible.5This frequ5

Open tubes (the flute) have these wave patterns:O n tubes (the flute) have these wave patterns:4

Open4

l = 0.5λ

l = λ

l = 1.5λ

l = 2λ

LOW NOTE(can’t get this

because of laminar flow)

HIGH NOTE



EXP 65The Doppler Effect

Get a pupil to do an impression of a racing car driv-ing past.

NEEEEEOWWWWWWW

High note → Low Note

G t a pupil to do an impression of a racing car driv-past.

NEEEEEOWWWWWWW

High note → Low Note

1Get a ing p1

Why does the note change? Is it that the car hap-pens to change speed just as it passes you? No, as it’s the same for everyone no matter where they stand.

Why does the note change? Is it that the car hap- to change speed just as it passes you? No, as

it s the same for everyone no matter where they stand.

2Why pens it’s th

2

Get the pupils to identify when the note is higher and when it is lower.

HIGHER NOTE - Coming towards them

LOWER NOTE - Going away from them.

Why does this happen?

The buzzer is always making the same frequency sound/same wavelength.

G t the pupils to identify when the note is higgher when it is lower.

HIGHER NOTE - Coming towards them

LOWER NOTE - Going away from them.

Why does this happen?

The buzzer is always making the same frequeency sound/same wavelength.

4Get tand w4

Buzzer coming towards you

Sound waves get squashed up so pitch appears to increase ‘NEEEEEEE’.

Buzzer going away from you

Sound gets stretched out so pitch appears to de-crease ‘YOWWWW’.

B zer coming towards you

nd waves get squashed up so pitch appears to increase ‘NEEEEEEE’.

Buzzer going away from you

Sound gets stretched out so pitch appears to de-crease ‘YOWWWW’.

5Buzz

Soun5

This effect is called the ‘Doppler Effect’. The same effect happens with light and has been one of the major pieces of evidence to support the Big Bang theory of the universe.

Next time you’re on a swing try screaming and get your mates to listen.

Thi effect is called the ‘Doppler Effect’. The same effect happens with light and has been one of the major es of evidence to support the Big Bang theory of the universe.

Next time you’re on a swing try screaming and get your mates to listen.

6This piece6

Get a buzzer and connect it to a battery with long flexible wires. Whizz the buzzer around your head and get the pupils to listen to the note.

Great demo, but be careful to check the wires, as the buzzer could fly off!

(9V PP3 with a 6V buzzer works fine.)

4Get a buzzer and connect it to a battery with llong

ble wires. Whizz the buzzer around yourr head and get the pupils to listen to the note.

Great demo, but be careful to check the wires, as the buzzer could fly off!

(9V PP3 with a 6V buzzer works fine.)

3Get a flexiband g

3

Coming towards you

Going away from you

Coming towards you

Going away from you



EXP 66 The Doppler Effect and the Big Bang

If the universe started with a Big Bang then things would fly off from the explosion with various differ-ent velocities. It’s like the start of a race.

If the universe started with a Big Bang then things ld fly off from the explosion with various differ-

ent velocities. It’s like the start of a race.1

If thewoulent v

1Imagine a race between a cyclist, a slow car and a racing car. Ready, Steady, GO!I gine a race between a cyclist, a slow car and a

ng car. Ready, Steady, GO!2Imagracin2

So,

whichever way you looked you’d see things moving away from you.

S

chever way you looked you’d see things moving away from you.

6So,

whic

Now imagine you’re in the slow car and you looked out of the front. What would you see? You’d see the racing car moving AWAY from you.

6N w imagine you’re in the slow car and you looked

of the front. What would you see? You’d see the racing car moving AWAY from you.

5Now out othe r

5

The racing car, which is going the fastest, has got the furthest. The slow car has travelled less distance and the cyclist that is going the slowest has travelled the least distance.

Th racing car, which is going the fastest, has got furthest. The slow car has travelled less distance

and the cyclist that is going the slowest has travelled the least distance.

3The rthe fuand t

3Now imagine you were in the slow car and you looked out the back. What would you see? You’d see the cyclist being left behind. If you couldn’t tell that you were moving AWAY you’d see the cyclist reversing away from you.

N w imagine you were in the slow car and you ed out the back. What would you see? You’d

see the cyclist being left behind. If you couldn’t tell that you were moving AWAY you’d see the cyclist reversing away from you.

4Now looksee t

4

some time later



EXP 67The Big Bang

Now, remember the Doppler Effect. If something’s giving off a wave and moving away from you its wavelengths get spread out. Remember the racing car noise?

N w, remember the Doppler Effect. If something’s ng off a wave and moving away from you its

wavelengths get spread out. Remember the racing car noise?

1Nowgivinwave

1This happens with light waves too. If a thing that’s emitting light is moving away from you the light wavelength increases, it becomes redder than it should be.

Thi happens with light waves too. If a thing that’s ting light is moving away from you the light

wavelength increases, it becomes redder than it should be.

2This emittwave

2

‘How do we know how red it should be?’ is a ques-tion for pupils to ask. (If it comes up). Just say for now that it’s to do with a thing called the ‘Hydrogen emission spectrum’. Avoid this if you can.

‘H w do we know how red it should be?’ is a ques- for pupils to ask. (If it comes up). Just say for

now that it’s to do with a thing called the ‘Hydrogen emission spectrum’. Avoid this if you can.

3‘Howtion fnow

3We’re on the Earth moving through space at 28,000 ms-1 or 14,000 mph (incredible speeds) but can you tell this sitting here in the classroom? NO. So we’re like the slow car in the race. We’re moving but we can’t tell.

W ’re on the Earth moving through space at 28,000 1 or 14,000 mph (incredible speeds) but can

you tell this sitting here in the classroom? NO. So we’re like the slow car in the race. We’re moving but we can’t tell.

4We’rms-1you t

4

If there was a Big Bang (a big race) the where ever we look we’d see things moving away from us. Is this the case?

If there was a Big Bang (a big race) the where ever ook we’d see things moving away from us. Is

this the case?5

If thewe lothis t

5

The only way this can happen is that everything around us is moving ‘relative to us’ away. Also we find by observation that things further away from us are moving away faster.

Th only way this can happen is that everything nd us is moving ‘relative to us’ away. Also we

find by observation that things further away from us are moving away faster.

7The arounfind

7

One last little aside. Some stars when we look at them are constantly shifting to red, then to blue, then to red and so on. Why would this be? Are they constantly going away then towards us again? They must be orbiting something. What could it be? A black hole perhaps?

O last little aside. Some stars when we look at m are constantly shifting to red, then to blue,

then to red and so on. Why would this be? Are they constantly going away then towards us again? They must be orbiting something. What could it be? A black hole perhaps?

9One themthen

9

Well yes it is, to a point. Everywhere we look we see galaxies and stars where light appears ‘redder’ than it should be. This is called Red Shift.

W ll yes it is, to a point. Everywhere we look we galaxies and stars where light appears ‘redder’

than it should be. This is called Red Shift.6

Well see gthan

6

This is a very famous image known as the Hubble Ultra Deep Field Image. It shows young galaxies from a very long way away. The light from there has taken a long time to get to us, so the galaxies look a lot like they would have looked around the time of the Big Bang.

This is a very famous image known as the Hubble Ultra Deep Field Image. It shows young galaxies from a very long way away. The light from there has taken a long time to get to us, so the galaxies look a lot like they would have looked around the time of the Big Bang.

The Big Bang theory suggests that this is because everything started moving at the same time (a big explosion), and just like the start of a race with the racing car, which has got furthest away by going the quickest.

Th Big Bang theory suggests that this is because ything started moving at the same time (a big

explosion), and just like the start of a race with the racing car, which has got furthest away by going the quickest.

8The everyexplo

8



EXP 68 Space Telescopes vs. Terrestrial Telescopes

What are the problems faced with telescopes that are mounted on the Earth?What are the problems faced with telescopes that

mounted on the Earth?1Whaare m1

The song ‘Twinkle Twinkle Little Star’ gives us a clue.

Stars don’t twinkle! It’s the atmosphere that’s con-stantly moving (because of convection) that distorts the light from the star. This is a real problem when we’re trying to see detail from distant objects.

Th song ‘Twinkle Twinkle Little Star’ gives us a .

Stars don’t twinkle! It’s the atmosphere that’s con-stantly moving (because of convection) that distorts the light from the star. This is a real problem when we’re trying to see detail from distant objects.

2The clue.2

The other problem is that the atmosphere absorbs a lot of the electromagnetic spectrum e.g. UV light and X-rays. This is good for life on Earth but bad for astronomers who may be trying to see these wavelengths as evidence for astronomical events. A star collapsing into a black hole may emit X or even gamma rays. You would not witness this even using a terrestrial (ground based) telescope.

Th other problem is that the atmosphere absorbs of the electromagnetic spectrum e.g. UV light

and X-rays. This is good for life on Earth but bad for astronomers who may be trying to see these wavelengths as evidence for astronomical events. A star collapsing into a black hole may emit X or even gamma rays. You would not witness this even using a terrestrial (ground based) telescope.

3The a lot and X

3

So what can astronomers do about it? Well we can put telescopes on mountains where the atmosphere is thinner to reduce the effects but we still have the absorption problem.

S what can astronomers do about it? Well we can elescopes on mountains where the atmosphere

is thinner to reduce the effects but we still have the absorption problem.

4So wput tis thi

4

These pic-tures were taken with the Hubble Space Telescope. Left is the Tarantula Nebula, and below is the Eagle Nebula.

These pic-tures were taken with the Hubble Space Telescope. Left is the Tarantula Nebula, and below is the Eagle Nebula.

We can send telescopes into space.

No atmosphere – good news.Very expensive – bad news.

W can send telescopes into space.

atmosphere – good news.Very expensive – bad news.

5We c

No a5

There’s a lovely story about the HST concave mir-ror problem. The mirror had a problem (the spare didn’t), but they didn’t find out until it was up in space… what a nightmare!

They had to go up and do a repair, which was not possible without the shuttle.

Th re’s a lovely story about the HST concave mir-problem. The mirror had a problem (the spare

didn’t), but they didn’t find out until it was up in space… what a nightmare!

They had to go up and do a repair, which was not possible without the shuttle.

7Therror pdidn

7

There are many telescopes in space, such as:

Hubble Space Telescope - HST• Infra Red Astronomical Satellite - IRAS• Cosmic Background Emissions – COBE•

There are even clusters of detectors that work to-gether to get 3D data from the solar wind from the sun.

Th re are many telescopes in space, such as:

Hubble Space Telescope - HSTInfra Red Astronomical Satellite - IRAS•Cosmic Background Emissions – COBE•

There are even clusters of detectors that work to-gether to get 3D data from the solar wind from the sun.

6Ther

H•6



EXP 69How Quicky Do We Orbit the Sun?

This is really great fun to work out from a couple of pieces of knowledge and some simple maths.Thi is really great fun to work out from a couple of

es of knowledge and some simple maths.1This piece1

So how far is the Sun from us?

x = v t = 300,000,000 x 480s =144,000,000,000m

S how far is the Sun from us?

x = v t = 300,000,000 x 480s =144,000,000,000m

4So h

4

It takes (t) 1 year to do this:

1 year = 365.25 days1 day = 24 hours1 hour = 60 minutes1 minutes = 60 seconds

So:

1 year = 365.25 x 24 x 60 x 60 = 31,557,600 seconds

It t kes (t) 1 year to do this:

1 year = 365.25 days1 day = 24 hours1 hour = 60 minutes1 minutes = 60 seconds

So:

1 year = 365.25 x 24 x 60 x 60 = 31,557,600 seconds

6It tak

1 6

So we’re travelling at:

v = x = 904,778,684,200m t 31,557,600s

= 28,670 ms-1

= 14.300 mph

Amazing! You can’t tell, can you?

S we’re travelling at:

v = x = 904,778,684,200m, , , t 31,557,600s

= 28,670 ms-1

= 14.300 mph

Amazing! You can’t tell, can you?

7So w

v 7

How far does the Earth travel to get round the Sun (i.e. in a year)? It’s the circumference of a circle (2πr or πd).

Distance (x) travelled

in a year = 2πr

= 2π x 144,000,000,000

= 904,778,684,200m

= (9.05 x 1011)m

H w far does the Earth travel to get round thee Sun in a year)? It’s the circumference of a cirrcle

(2πr or πd).d).

Distance (x (x ) travelled

in a year = 2πr

= 2π x 144,000,000,000

= 904,778,684,200m

= (9.05 x 1011)m1

5How (i.e. (2πr

5

Ask pupils how long it takes for the Sun’s light to get to the earth (take guesses).

Answer: 8 minutes (8 x 60 = 480s)

Ask how fast light travels (take guesses).

Answer: 300,000,000 ms-1

A k pupils how long it takes for the Sun’s ligght to o the earth (take guesses).

Answer: 8 minutes (8 x 60 = 480sx )

Ask how fast light travels (take guesses).

Answer: 300,000,000 ms-1

2Ask get to2

What’s the relationship between velocity, distance and time?

x = vt

What’s the relationship between velocity, disttance time?

x = vt

3Whaand t3



EXP 70

EXP 71

EXP 72

EXP 73

Leeuwenhoek’s Microscope

White Light and Colour

Invisible Writing

A Cat’s Sight

Twist a single strand of wire so that you get a loop at the end of about 3mm across.

Dip the loop into water and a small droplet will form in the loop.

Use the droplet as a magnifying glass to look at objects close up.

T ist a single strand of wire so that you get a loop at the end of ut 3mm across.

Dip the loop into water and a small droplet will form in the loop.

Use the droplet as a magnifying glass to look at objects close up.

1Twisabou1

White light is all the colours of the rainbow (Red, Orange, Yellow, Green, Blue, Indigo and Violet, ROYGBIV) added together. We can see this if we split them up using a pen tube to refract the light. Different colours refract by different amounts and so the light splits into a spectrum.

White light is all the colours of the rainbow (Red, Orange, Yellow, en, Blue, Indigo and Violet, ROYGBIV) added together. We

can see this if we split them up using a pen tube to refract the light. Different colours refract by different amounts and so the light splits into a spectrum.

1WhitGreecan s

1

Draw with a red pen on a white surface. Look through the green filter. You can still see the pat-tern. Hold up a red filter and the pattern should disappear.

D w with a red pen on a white surface. Look ugh the green filter. You can still see the pat-

tern. Hold up a red filter and the pattern should disappear.

1Drawthroutern

1

Cats only see a few colours, not as many as humans.C t only see a few colours, not as many as humans.1

Cats 1

Why does this happen? The white background reflects all colours. The red writing reflects only red light. The filter only lets through red light so the red writing appears on a red background. It disappears!

Why does this happen? The white background cts all colours. The red writing reflects only red

light. The filter only lets through red light so the red writing appears on a red background. It disappears!

2Why reflelight

2



EXP 74Polarisation

Light is a transverse wave, but its displacement is in many different directions.Li ht is a transverse wave, but its displacement is in many different directions.1

Ligh 1

This is a wave of light travelling to the right. See how the displacements are in many different directions? It is made up of these:Thi is a wave of light travelling to the right. See how the displacements are in many different directions? It is

e up of these:2This made2

With displacements in many different directions the light is called unpolarised. We can put it through a filter that will allow through displacements in one plane only.With displacements in many different directions the light is called unpolarised. We can put it through a filter that

allow through displacements in one plane only.3Withwill 3



As there is less energy coming through the filter than hitting it, the intensity of the light drops.A there is less energy coming through the filter

hitting it, the intensity of the light drops.5As ththan 5

Polarising also occurs when light is reflected from a smooth surface e.g. car windscreens, the surface of water.

P l rising also occurs when light is reflected from a oth surface e.g. car windscreens, the surface of

water.6

Polarsmoowate

6

It’s a bit like forcing the light through a grill of bars. Only displacements going the same way as the grill of bars get through.It’ a bit like forcing the light through a grill of bars. Only displacements going the same way as the grill of bars

hrough.4It’s aget th4

If another filter is introduced and is the same way up as the first one then the polarised light can still get through.If nother filter is introduced and is the same way up as the first one then the polarised light can still get through.7

If an7

However, if the filters are at right angles to each other (perpendicular) then no light can get through. Total dark-ness!H wever, if the filters are at right angles to each other (perpendicular) then no light can get through. Total dark-

!8Howness8

Here the two filters have their angle of polarisation perpendicular to each other so no light gets through both and the scene is dark.

H e the two filters have their angle of polarisation endicular to each other so no light gets through

both and the scene is dark.2

Hereperpboth

If we put a polarising filter so that its plane of polarisation is perpendicular to the reflected light the reflected light can no longer be seen and we see the fish below more clearly.

If e put a polarising filter hat its plane of

polarisation is perpendicular to the reflected light the reflected light can no longer be seen and we see the fish below more clearly.

2If we so thpolar

2

Place the filter perpendicular to the polarised light coming out of the calculator and the screen disappears.

Pl e the filter perpendicular e polarised light coming

out of the calculator and the screen disappears.

4Place to thout o

Light is polarised on reflection so the light being reflected from the surface of this fish tank is polarised but the light coming from the fish is not.

Li ht is polarised on reflection he light being reflected

from the surface of this fish tank is polarised but the light coming from the fish is not.

1Ligh so thfrom

1



EXP 75

EXP 76

Polarising Filters

Polarisation on Reflection

Look through two polarising filters. Rotate one filter a full circle and watch what happens.

Here the two filters have their plane of polarisation in line and light gets through both.

2L k through two polarising filters. Rotate one filter

l circle and watch what happens.

Here the two filters have their plane of polarisation in line and light gets through both.

1Looka ful1

An LCD display uses reflection from a back surface and a polarising filter to block out light to show numbers on a calculator. You can see how it’s polarised using one filter.

4A LCD display uses reflection from a back surface

a polarising filter to block out light to show numbers on a calculator. You can see how it’s polarised using one filter.

3An Land a filter

3



EXP 77 Other Uses of Polarisation

Get a piece of sticky tape and fold it over and over on itself. Place it between two polarising filters and see the pattern.

G t a piece of sticky tape and fold it over and over self. Place it between two polarising filters and

see the pattern.1

Get a on itsee th

1

Rotate one filter and see the pattern change. The sticky tape changes the plane of polarisation for dif-ferent wavelengths (colours) by different amounts. You can make some excellent art with this effect.

R tate one filter and see the pattern change. The ky tape changes the plane of polarisation for dif-f-f

ferent wavelengths (colours) by different amounts. You can make some excellent art with this effect.

2Rotastickferen

2

Look at this sample of polythene. The colours gather at the most stressed part of the sample. This technique can be used to analyse stress patterns in complicated shapes. There is usually a stress con-centration at any nicks, scratches or breaks in the material.

L k at this sample of polythene. The colours er at the most stressed part of the sample. This

technique can be used to analyse stress patterns in complicated shapes. There is usually a stress con-centration at any nicks, scratches or breaks in the material.

3Lookgathetechn

3

You can see the stresses this ruler has gone through in manufacture. The process has left its mark in the polarised light.

Y can see the stresses this ruler has gone through anufacture. The process has left its mark in the

polarised light.4

You in mpolar

4



EXP 78Standing Waves and Balafons

If you hit a piece of wood a wave travels up and down the length of the wood. The wave travelling up interferes with the wave travelling down and a standing wave is produced.

If ou hit a piece of wood a wave travels up and n the length of the wood. The wave travelling

up interferes with the wave travelling down and a standing wave is produced.

1If yodownup in

1The points of constructive interference are called antinodes (where the wave is big).

The points of destructive interference are called nodes (where the waves have cancelled each other out).

ThTh poiintts of f consttructitive i i tnterfference are ed antinodes (where the wave is big).

The points of destructive interference are called nodes (where the waves have cancelled each other out).

2The calle2

So, no vibration is occurring at ¼l or ¾l, but lots of vibration is happening at the ends and at the middle.S no vibration is occurring at ¼l or ¾l, but lots of

ation is happening at the ends and at the middle.3So, nvibra3

The length of wood controls the frequency of the note. See how the blocks of wood are tied with string only at ¼l and ¾l on this balafon?

Have a go at making one!

Th length of wood controls the frequency of the . See how the blocks of wood are tied with

string only at ¼l and ¾l on this balafon?

Have a go at making one!

5The note. string

5

Now if we support the wood below the nodes where nothing is happening, the waves/vibrations are unaffected and the note of the balafon rings on. However, if we support the wood anywhere else the vibrations are killed and the note stops. We get a dull ‘thunk’ sound.

N w if we support the wood below the nodes re nothing is happening, the waves/vibrations

are unaffected and the note of the balafon rings on. However, if we support the wood anywhere else the vibrations are killed and the note stops. We get a dull ‘thunk’ sound.

4Now wherare u

4

l

nodenode

wood vibrating just after a hit

wave pattern of vibration

antinode antinode antinode

¼l



EXP 79 Young’s Double Slits

You will need either a dark room for this or a dark box that you can look into.Y will need either a dark room for this or a dark

that you can look into.1You box t1

λ = sinθ or x = tanθs D

If D is huge (a few metres) compared to s (fractions of a mm) then θ is very small.

λλ = sinθ or x = tanθs D

If D is huge (a few metres) compared to s (fraactions of a mm) then θ is very small.

5λs 5

Young’s double slits uses this equation:

λ = x s D

Y ng’s double slits uses this equation:

λ = x s D

2Youn

λ 2

For small θ sin θ ≈ tan θ

i.e.

λ = x or λ = xs s D D

F small θ sin θ ≈ tan θ

λ = x or λ = xs s D D λ

6For s

i.e.6

Now, the little triangle and the large dotted triangle are called ‘similar triangles’ (same angles, same ratio of sides).N w, the little triangle and the large dotted triangle are called ‘similar triangles’ (same angles, same ratio of

s).4Nowsides4

Dλ

θ

θ

xs

Where does this equation come from? If we shine monochromatic light (one colour) through two slits that are s distance apart we have two coherent sources of light. The central maximum is where the two waves have trav-elled the same distance, so they are in phase and add up to a bright spot. Another spot appears x away from the central maximum where the path difference = λ i.e. the waves are back in phase so they add up.

Where does this equation come from? If we shine monochromatic light (one colour) through two slits that are s ance apart we have two coherent sources of light. The central maximum is where the two waves have trav-

elled the same distance, so they are in phase and add up to a bright spot. Another spot appears x away from the xcentral maximum where the path difference = λ i.e. the waves are back in phase so they add up.

3Whedistaelled

3

LASER

D

λ

θ

θ

xs

central maximum

next maximum



EXP 80Measuring the Wavelength of Light

For this you will need to use this formula:

λ = x s D

Use this to remember it: too much λ leads to excess (xs) drinking (D) !

F this you will need to use this formula:

λ = x s D

Use this to remember it: too much λ leads to eexcess (xsxs) drinking (D ) !

1For t

λ = 1

If we can measure x, s and D in Young’s Double Slit Experiment then we can find the wavelength of light. Excellent!

If e can measure x, s and D in Young’s Double Experiment then we can find the wavelength of

light. Excellent!2

If we Slit Elight

2

So you have slits at 0.25mm separation (s = 0.25 x 10-3m). You need to measure D, but remember it should be at least a few metres.

S ou have slits at 0.25mm separation (s = 0.25 xm). You need to measure D, but remember it

should be at least a few metres.5

So y10-3shou

5

Use λ = xs to find the wavelength of light. D

The answer should be around 650nm, which is 650 x 10-9 m.

λ = xs to find the wavelength of light.D

The answer should be around 650nm, which is 650 x 10-9 m.

7 Use 7

For the diffraction slits you can use a special double slit slide, or you can make your own:

Use a microscope slide painted black, then make two tiny, straight scratches 0.25mm apart.

F the diffraction slits you can use a special double slit slide, ou can make your own:

Use a microscope slide painted black, then make two tiny, straight scratches 0.25mm apart.

4For tor yo4

You should see fringes of light like this:

Now measure across 10 of them (from the middle of the fringes) and divide by 10 to get fringe separation x (x will be around 1mm approximately).

Y should see fringes of light like this:

Now measure across 10 of them (from the middle of the fringes) and divide by 10 to get fringe separation x (x x (x will be around x 1mm approximately).

6You

6

When you do this experiment remember to have the screen about 4m away from the laser pen.

(WATCH OUT! In this picture we have not made sure that D is big – you cannot measure it like this in the experiment!)

When you do this experiment remember to have creen about 4m away from the laser pen.

(WATCH OUT! In this picture we have not made sure that D is big – you cannot measure it like this in the experiment!)

3Whethe s3



EXP 81 Dice to Show Radioactive Decay

This is a great demo for schools that have no radio-active sources. The nuclei of radioactive elements are unstable. There’s a chance that they may decay and emit a radioactive particle.

Thi is a great demo for schools that have no radio-ve sources. The nuclei of radioactive elements

are unstable. There’s a chance that they may decay and emit a radioactive particle.

1This activare u

1There are two things that determine how radioactive a sample is:

The chance of decay (• λ). The higher the chance the more particles will be emitted over a given time.

The number of radioactive atoms you may have • (N). The more atoms you have the more parti-cles will be emitted over a given time.

Th re are two things that determine how radioactive mple is:

The chance of decay (• λ(λ( ). The higher the chance the more particles will be emitted over a given time.

The number of radioactive atoms you may have •(N). The more atoms you have the more partiN). The more atoms you have the more partiN -cles will be emitted over a given time.

2Ther a sam2

The chance of decay never changes as it is part of the make up of each atom. The number of radioac-tive atoms will decrease as more and more of them decay. The lovely thing is that dice do the same.

Th chance of decay never changes as it is part of make up of each atom. The number of radioac-

tive atoms will decrease as more and more of them decay. The lovely thing is that dice do the same.

3The the mtive a

3

If we say that throwing a six represents the atom decaying and the number of dice represents the number of atoms then we can do the following ex-periment. Each throw represents a step in time.

If e say that throwing a six represents the atom aying and the number of dice represents the

number of atoms then we can do the following ex-periment. Each throw represents a step in time.

4If we decanumb

4

You will need 100 dice.

Count the dice (there may be a few missing). Throw them all and count the number that come up six. Remove these dice from the experiment. Re-throw the remaining dice and again count and remove the sixes. Continue until you get down to only a few dice

Y will need 100 dice.

nt the dice (there may be a few missing). Throw them all and count the number that come up six. Remove these dice from the experiment. Re-throw the remaining dice and again count and remove the sixes. Continue until you get down to only a few dice

5You

Coun5



Don’t worry if the number of sixes doesn’t fit the pattern exactly. That’s a good thing, radioactivity does the same. Point out to students that activity (A) (the number of sixes) is given by:

Activity = chance of x number decay remaining

A = λ N

So if you had 60 dice:

A = 1 x 60 6

= 10

D ’t worry if the number of sixes doesn’t fit t the ern exactly. That’s a good thing, radioacttivity

does the same. Point out to students that activvity (A(A) (the number of sixes) is given by:

Activity = chance of f f x number decay remainingivity x

A = λ N

So if you had 60 dice:

A = 1 x 60 6

= 10

7Donpattedoes

Now we need to plot a graph of number remaining (N) against throw number. For this you will need graph paper, pencils and rulers.

N w we need to plot a graph of number remaining against throw number. For this you will need

graph paper, pencils and rulers.8

Now (N) agraph

8

Record results:

No. of throws No. of sixes No. of remaining dice

0 100

1 12 88

2 10 78

7R ord results:

of throws No. of sixes No. of remaining dice

0 100

1 12 88

2 10 78

6Reco

No. o6

xx

x xx x x x x x x x x x x x x

100

Num

ber

rem

aini

ng

Throws

A beautiful exponential decay curve. (Don’t go through each point – draw a smooth curve that fol-lows the trend).

xx

x xx x x x x x x x x x x x x

100

Num

ber

Num

ber

rem

aini

ng

ThrowsThrows

A beautiful exponential decay curve. (Don’t go ugh each point – draw a smooth curve that fol-

lows the trend).9

A bethroulows

9

N

Throws

Don’t worry too much about getting into what ‘ex-ponential’ means. Analyse the graph like this:

The equation A = λN leads to this graph.

N

Throws

D ’t worry too much about getting into what ‘ex-ntial’ means. Analyse the graph like this:

The equation A = λN leads to this graph.N

10Don’t ponen10



The time it takes to halve the remaining number of atoms never changes. It’s called the half life and has the symbol T½ (this is not T x ½, treat T½ as a single symbol).

It is related to the chance of decay (λ) in the equa-tion below:

T½ = 0.69 λ

But don’t tell them this yet!

Th time it takes to halve the remaining numbber of s never changes. It’s called the half life and

has the symbol T½T½T (this is not T x ½, treat T½T½T as a single symbol).

It is related to the chance of decay (λ (λ ( ) in the e equa-tion below:

T½T½ = 0.69 λ

But don’t tell them this yet!

12The tatoms has th

12Go back to the graph and using different start and stop points find a value for T½ from your results. Ig-nore any T½s that seem inaccurate (i.e. are different from all the others). What value of T½ do you get?

A good value would be around 4.2, but anything near 4 is good.

G back to the graph and using different start and points find a value for T½T½T from your results. Ig-

nore any T½T½s that seem inaccurate (i.e. are different from all the others). What value of T½T½T do you get?

A good value would be around 4.2, but anything near 4 is good.

13Go bastop pnore

13

Throws

N

And this graph has a special property:

Time taken to It takes the And again it takes This time is

fall to half same time to the same time to called T½.

remaining fall to half again halve again

A d this graph has a special property:

Time taken to It takes the And again it takes This time is

fall to half f same time to the same time to called T½.

remaining fall to half again halve again

Throws

N

100

50

2512.50

11And t

11

Ask the students if they can find a relationship between T½ and λ. To get them to do this ask what would happen to T½ if we made the chance of decay greater e.g. by throwing coins instead of dice, where ‘heads’ = decay. If they can’t think of the answer then you can do this extra experiment.

A k the students if they can find a relationship een T½T½T and λ. To get them to do this ask what

would happen to T½T½ if we made the chance of decay greater e.g. by throwing coins instead of dice, where ‘heads’ = decay. If they can’t think of the answer then you can do this extra experiment.

14Ask tbetwewould

14



Try a slightly different experient now. You will need 100 dice, graph paper, pencils and rulers.

Repeat the previous experiment but double the chance of decay by removing dice if they come up with a 6 or a 3 (λ = 1/3). Plot the graph again. Find T½.

T a slightly different experient now. You will need dice, graph paper, pencils and rulers.

Repeat the previous experiment but double the chance of decay by removing dice if they come up with a 6 or a 3 (λ = 1/3(λ = 1/3( ). Plot the graph again. Find T½T½T .

15Try a 100 d15

If we double the chance of decay (λ) then the value of T½ halves.

So T½ is inversely proportional to λ.

T½ 1 or T½ = constant λ λ

Rearranging

T½ x λ = constant

If e double the chance of decay (λ (λ ( ) then the value ½ halves.

So T½T½T is inversely proportional to λ.

T½T½T 1 or T = constant λ λ T½ T½ T

Rearranging

T½T½T x λ = constant

16If we of T½T½T16

Using your two sets of results, find the constant.

I’ve done some approximately here:

4.1 x 1 = 0.699 6

2.1 x 1 = 0.69 3

Average ≈ 0.69

So in fact the equation becomes:

T½ = 0.69

λ

U i g your two sets of results, find the constaant.

done some approximately here:

4.1 x 1 = 0.699 6x

2.1 x 1 = 0.69 3x

Average ≈ 0.69

So in fact the equation becomes:

T½ T½ T = 0.69 λ

17Using

I’ve d17

Plotting activity (A) against throws gives the same exponential decay graph with the same values of T½ (try it if you like). You will find it’s less convincing due to the random nature (random in that you do not know which dice will decay) of decay. However, in real life we actually take this reading with a Geiger counter. To count actual undecayed atoms would be impossible and take a very long time.

Pl tting activity (A(A( ) against throws gives the same nential decay graph with the same values of T½T½

(try it if you like). You will find it’s less convincing due to the random nature (random in that you do not know which dice will decay) of decay. However, in real life we actually take this reading with a Geiger counter. To count actual undecayed atoms would be impossible and take a very long time.

19Plottiexpon(try it

9There’s a lot of maths that we can use to prove this (note ln2 = 0.693) and we could go into it but don’t bother if the syllabus does not require it).

19Th e’s a lot of maths that we can use to prove this

ln2 = 0.693) and we could go into it but don’t bother if the syllabus does not require it).

18There(note bothe

18



EXP 82 Circular Motion

What affects the amount of force needed to keep something moving in a circle? Something going round in a circle is constantly changing direction. It takes more force to change the direction of a bigger mass.

What affects the amount of force needed to keep ething moving in a circle? Something going

round in a circle is constantly changing direction. It takes more force to change the direction of a bigger mass.

1Whasomeroun

1

Conclusion: The force (F) required to keep some-thing of mass (m) going round a circle of radius (r) at a speed (v) is given by:

F = mv2

r

If you are careful this works very well.

C clusion: The force (F) required to keep soomeF) required to keep someF -g of mass (m) going round a circle of radiius (r)

at a speed (v) is given by:

F = mv2

r

If you are careful this works very well.

7Concthing at a s

7

So is F m ?

F v ?

F 1/r ?

Let’s try an experiment to find out.

s F m ?

F v ?

F 1/r ?

Let’s try an experiment to find out.

3 So is 3To try Whizzo Bungs you will need: String, tube, bung, 100g (1N) masses, stop watch, ruler, scales.

The string should be about 1.5m long. Tie one end of the string to the bung, thread the other end through the tube then tie it into a loop so you can hook the masses on it. When you use the Whizzo Bung hold onto the tube and swing the bung around the top of your head in big circles.

T try Whizzo Bungs you will need: String, tube, g, 100g (1N) masses, stop watch, ruler, scales.N) masses, stop watch, ruler, scales.N

The string should be about 1.5m long. Tie one end of the string to the bung, thread the other end through the tube then tie it into a loop so you can hook the masses on it. When you use the Whizzo Bung hold onto the tube and swing the bung around the top of your head in big circles.

4To trbung4

The faster something is moving round the circle the more quickly it is changing direction. So, going faster means more force is required. If something is going round a smaller radius it is changing direction more quickly, so a smaller radius means more force is required.

Th faster something is moving round the circle the e quickly it is changing direction. So, going

faster means more force is required. If something is going round a smaller radius it is changing direction more quickly, so a smaller radius means more force is required.

2The morefaste

2

To do the experiment:

Measure the mass of the bung.1. Whizz the bung around your head trying to keep 2. the speed constant.Keep the weights at a constant height but not by 3. holding them, just by whizzing the bung around.Time how long it takes for the bung to com-4. plete 10 circles. Divide by 10 to get (T) (count 1,2,…,10).At the end of each set of 10 grab the string to 5. keep (r) so you can measure it.Repeat for weights between 6. 1N and 6N (F).Calculate 7. v = 2πr/TDraw a table 8. m = ?g Compare 9. mv2/r to F. They should be the same. Be careful with metres.

T do the experiment:

Measure the mass of the bung.Whizz the bung around your head trying to keep 2.the speed constant.Keep the weights at a constant height but not by 3.holding them, just by whizzing the bung around.Time how long it takes for the bung to com-4.plete 10 circles. Divide by 10 to get (T) (count T) (count T1,2,…,10).At the end of each set of 10 grab the string to 5.keep (r) so you can measure it.Repeat for weights between 6. 1N and N 6N (N F).F).FCalculate 7. v = 2πr/TDraw a table 8. m = ?g Compare 9. mv2/r2 to r F. They should be the same. Be careful with metres.

5To do

M1.5

Use this table for your results.

T/s r/m 2πr 2πr/T mv2/r F

U this table for your results.

r/m 2πr 2πr/T mv2/r2 F

6Use

T/s6



EXP 83

EXP 84

Sticky Balloon

Dancing Crumbs

Break off a few crumbs from a biscuit onto a plate.

B ak off a crumbs

from a biscuit onto a plate.

1Breafew cfrom

1

Stretch cling film over the plate.

St tch cling over the

plate.2

Stretfilm plate

2

Rub the cling film with a tissue.

Electrons are rubbed onto the clingfilm, the saucer’s and crumbs electrons are repelled making them positive.

R b the cling film with a tissue.

trons are rubbed onto the clingfilm, the saucer’s and crumbs electrons are repelled making them positive.

3Rub

Elect3

Watch the crumbs jump and dance.

The crumbs jump up to the negative, gain electrons, become neutral and fall down.

W tch the crumbs jump and dance.

crumbs jump up to the negative, gain electrons, become neutral and fall down.

4Watc

The 4

Rub a balloon on your head.

Electrons are rubbed onto the balloon.

R b a balloon on your head.

trons are rubbed onto the balloon.1

Rub

Elect1

Touch the balloon onto the wall.

Electrons are repelled from the wall so the wall becomes positive and the balloon is attracted to the wall.

T ch the balloon onto the wall.

trons are repelled from the wall so the wall becomes positive and the balloon is attracted to the wall.

2Touc

Elect2

Now watch what happens when you put the strip next to a thin stream of water:

N w watch what happens when put the strip next to a thin

stream of water:2

Now you pstrea

2You will need a polythene strip, a cloth, water and a bottle. First, rub the strip very fast with a cloth.

Y will need a thene strip,

a cloth, water and a bottle. First, rub the strip very fast with a cloth.

1You polyta clo

1



EXP 85

EXP 86

Bending Water

Attraction and Repulsion

Water bends as the negative (-ve) charge is attracted towards the positive (+ve) polythene strip. They get nearer than the repelled +ve charges, so they are attracted more than the +ve charges are repelled, and the water bends.

W ter bends as the negative (-ve) charge is attracted towards positive (+ve) polythene strip. They get nearer than the

repelled +ve charges, so they are attracted more than the +ve charges are repelled, and the water bends.

3Watethe prepel

3

- +- +

- +- +

- +

+ + + + ++

This time you will need two polythene (opaque) strips, two acetate (see-through) strips, two watch glasses and a cloth. Put the watch glasses back to back and lay a polythene strip over the top so it can rotate freely. Rub the end of the other strip with the cloth then put it near and see what happens.

Like charges repel!

Thi time you will need two polythene (opaque) s, two acetate (see-through) strips, two watch

glasses and a cloth. Put the watch glasses back to back and lay a polythene strip over the top so it can rotate freely. Rub the end of the other strip with the cloth then put it near and see what happens.

Like charges repel!

1This stripsglass

1

see what h

+appens.

+

Try the experiment again, this time with the acetate strips:

Once more with one acetate strip and one polythene strip:

Opposites attract, like (similar) charges repel!

T the experiment again, this time with the a acetate s:

Once more with one acetate strip and one poolythene strip:

Opposites attract, like (similar) charges repel!

2Try tstrips2

lik

+h

_h

_

i

_



EXP 87Hooke’s Law and the Spring Constant (k)

When you put a weight on a spring the spring extends – it gets longer. This ‘extra’ length is called the extension (x).

When you put a ght on a spring

the spring extends – it gets longer. This ‘extra’ length is called the extension (xx).

1Wheweigthe s

1The amount a spring extends for a given weight is called its stiffness.Th amount a spring extends for a given weight is

ed its stiffness.2The calle2

So,

stiffness = up = F along x

k is measured in Nm-1

S

stiffness = upp = F alongg x

k is measured in Nm-1

7So,

7

Investigation – finding the stiffness of different spring arrangements:

Load up the spring with the weights. For different weights 100g – 600g (1N – 6N) measure the exten-sion.

I stigation – finding the stiffness of different ng arrangements:

Load up the spring with the weights. For different weights 100g – 600g (1N – 6N) measure the extenN) measure the extenN -sion.

3Invessprin3

Repeat the whole experiment for 2 springs in series and parallel.

Remember to keep your results for EXP 88 and 89!

R eat the whole experiment for 2 springs in series parallel.

Remember to keep your results for EXP 88 and 89!

8Repeand p8

Get a table of the results:

Force/N Extension/m

0 01 …2 … ... …6 …

G t a table of the results:

ce/N Extension/m

0 01 …2 … ... …6 …

4Get a

Forc4

Plot this graph:

gradient = stiffness (k)

Pl t this graph:

gradient = stiffness (k)

5Plot

5 F

x

To find the gradient: Gradient = up/along

F = up

x = along

T find the gradient: Gradient = up/along

F = up

x = along

6To fi

6F

x



EXP 88 Simple Harmonic Motion with a Spring

Hang a 500g mass from a spring at-tached to a branch of a tree. Pull the mass down (not too far) and let it go. Time 10 full bounces of the spring (from a start, back to the start).

H g a 500g mass m a spring at-

tached to a branch of a tree. Pull the mass down (not too far) and let it go. Time 10 full bounces of the spring (from a start, back to the start).

1Hangfromtache

1It should take the same time for small oscillations as it does for big oscillations. This is called ‘iso-chronous’. All simple harmonic oscillations are isochronous.

It hould take the same time for small oscillations does for big oscillations. This is called ‘iso-

chronous’. All simple harmonic oscillations are isochronous.

2It shoas it chron

2

Now plot some graphs.

So,

T = 2π√( m ) k

N w plot some graphs.

T = 2π√( m ) k(

7Now

So,7

There are two things that affect the time for one oscillation. What do you think they are? Mass (m) and stiffness of the spring (k). In what way do you think they will affect it? What will more mass make the oscillations time (T) do? What will a stiffer spring make the time (T) do?

Th re are two things that affect the time for one llation. What do you think they are? Mass (m)

and stiffness of the spring (k). In what way do you think they will affect it? What will more mass make the oscillations time (T) do? What will a stiffer T) do? What will a stiffer Tspring make the time (T) do?T) do?T

5Ther osciland s

5

How can this be? The mass has further to travel if you pull it down further to start with BUT the spring also puts a larger force on the mass so it accelerates more. This compensates for the longer distance, so the time for one oscillation (T) stays the same.

H w can this be? The mass has further to travel if pull it down further to start with BUT the spring

also puts a larger force on the mass so it accelerates more. This compensates for the longer distance, so the time for one oscillation (T) stays the same.T) stays the same.T

4How you palso

4It should take the same time for small oscillations as it does for big oscillations. This is called ‘iso-chronous’.

All simple harmonic oscillations are isochronous.

It hould take the same time for small oscillattions does for big oscillations. This is called ‘ ‘iso-

chronous’.

All simple harmonic oscillations are isochronous.

3It shoas it chron

3

Investigation: The effect of mass on the time for one oscillation. You will need springs, masses and stopclocks. Vary the mass between 100g and 600g. Time 10 oscillations then ÷10 to get (T)

Investigation: The effect of spring constant (k) on T.

k ½ k 2k

I stigation: The effect of mass on the time for oscillation. You will need springs, masses and

stopclocks. Vary the mass between 100g and 600g. Time 10 oscillations then ÷10 to get (T)T)T

Investigation: The effect of spring constant (k) on T.T.T

k ½ k 2k

6Inveone ostopc

6

T

√mT

m

T

√k



EXP 89Simple Harmonic Motion with a Pendulum

Repeat your spring mass investigation, but this time using string and masses to create a pendulum.

Only swing the pendulum a small amount, other-wise the string starts to go slack and the pendulum misbehaves.

R eat your spring mass investigation, but this time g string and masses to create a pendulum.

Only swing the pendulum a small amount, other-wise the string starts to go slack and the pendulum misbehaves.

1Repeusing 1

In fact,

T = 2π√( l ) where g = 9.81 ms-2. g

So the gradient of T against √l gives:

T = 2π√l √g

Check your graph to see if this is true.

I fact,

T = 2π√( l ) where g = 9.81 ms-2. g( g(

So the gradient of T against √l gives:

T = 2π√l√ √g√√

Check your graph to see if this is true.

5In fa

T 5

This is also an isochronous oscillator. What factors do you think will affect the time for one oscillation? Possibly mass (m)? Possibly length (l)?

Thi is also an isochronous oscillator. What factors ou think will affect the time for one oscillation?

Possibly mass (m)? Possibly length (l)?l2

This do yoPoss

2

Time 10 oscillations for different lengths of string. Divide by 10 to get T. Measure l to the centre of mass of the masses.

Ti e 10 oscillations for different lengths of string. de by 10 to get T. Measure l to the centre of T. Measure l to the centre of T

mass of the masses.3

TimeDividmass

3

Make a results table, and then use it to plot two graphs:

l/m T/s

M ke a results table, and then use it to plot two hs:

l/m T/s

4Makgraph4

T

l

T

√l

Equipment List 2010

Item School Kit x 3 Teacher Training

1 Leslie cube Tin can 1 12 Laboratory thermoter 150mm green spirit 2 23 Ball & ring expansion kit 1 14 Black paint block 1 15 Graph paper 2/10/20 ream 1 16 Protractors 100mm dia 30 107 Set Squares 60’ 145mm hyp 24 128 Erasers 30 x 20 x 8mm 40 249 Sharpeners Single hole metal pencil 14 810 Drawing compass 100mm 30 1011 Plastic pockets 100 20012 Triple beam balance 1 113 Periodic table chart 720 x 520mm 1 114 9mm dowel 150mm long 20 1015 Wood V blocks 100x30x50mm 20 1016 NYLON G clamps small 75mm mouth 20 1017 Boyle’s law indicator 1 118 Calculator Albertz 2 1 119 Slinky 1 120 Personnel scales Newtons 1 121 100ml measuring cylinder 2 222 Marble 6 623 Balloons 250 25024 Corks 16mm (diameter small end) 20 1025 CDs 20 1026 Araldite (2 x resin & bonding tubes) 1 127 1m ruler 40 2028 Knife edge/pivot, Moldings 50mm 20 1029 String ball 500g 1 130 Scissors economy 12 1231 Single pulley 20 1032 Double pulley 1 133 1 kg hanger and mass set 10 534 1ml syringe 10 1035 20ml syringe 10 1036 3mm clear plastic tube, metres 5m 5m37 A4 paper ream 1 138 Newton meters 10N/100g 20 10

39 Optics pin 100g 100g40 White card 280g a sheet 100 10041 Cotton reel 30 1042 Pencils HB 150 5043 2 litre pop bottle (empty) 1 144 30cm ruler Polythene 60 2045 50m sports tape 1 146 Stop watch, basic 10 547 Stop watch batteries 10 3548 Toy car 2 249 Car track Cunduit lid CEF 1 150 Blue tack 120g 6 651 Sticky tape roll 6 652 Rokit kit 1 153 Foot pump (michellin) 1 154 Bendy straws (large dia) 250 pk 2 155 500ml plastic measuring beaker 2 256 Polystyrene ball 25mm diameter 20 2057 Bouncing ball 2 258 Matches, large box cooks 1 159 Conducting bars 5Pk Al,Cu,Fe,brass, glass 1 160 Aluminium plate 100 x 250mm 1 161 Black metal plate 150mm2 1 162 Candles 6 663 Rubber band tub 1 164 Match sticks 500 50065 Drawing pin 2 266 Empty syrup tin 1 167 Rubber bung 19/22.5mm pk10 dia single hol e 1 468 Brass tube (pk 300mm) for bung 5/4.1mm 1 169 Capilliary tube 1 170 Glass / plastic cappillary tube 1 171 Detergent small bottle 1 172 Cotton thread, reel 1 173 Wire 0.6m length 0.6 0.674 Vinyl record 1 175 Long self tapping Screw 2 276 Washers 3 377 Strong convex lens FL 150mm 1 1

78 Plano concave FL 150mm 1 179 Flat mirrors A6 size 5 580 Laser 3 381 Large Parabolic mirror 300mm dia 1 182 Small mirrors ct down A6 2 283 Black card pk100 1 184 Double sided tape 1 485 Coloured filters 6 686 Coin (old pennies) 2 287 Small glass pain 1 188 Acrylic block 115 x 65 x 20mm 1 189 Prism Glass R/angle 50mm size 1 190 Lens Biconvex 100mm FL 10 591 Greaseproof paper 457mm x 710mm 50 5092 Pin Dressmakers 30mm 40g pack 1 193 Wooden block 50 x 50 x 50 mm 1 194 Grey box sig gens 1 195 3mm rubber cord 2m 1 196 Whirling tube 1 197 6V Buzzer 1 198 AA batteries pk 4 Duracell 1 199 4 x AA cell holder, press stud 1 1100 Heavy duty PP3 clip(press stud) 1 1101 2 section terminal block 2 2102 2 core cable 2m 1 1103 Screwdriver (v.small) 1 1104 Wire (1mm diameter) 1m 1 1105 BIC pen as prism (red) 10 10106 Polarising filters slide type 2 2107 Red laser pointer 3 12108 AAA Duracell for laser pk4 1 1109 Young’s slits 1 1110 Dice 120 120111 Whizzo bung 1 1112 Tissue (box) 1 1113 Cling film (roll) 1 1114 Cloth for rubbing (lab coat rag) 1 1115 Watch glasses 2 2116 Slide file binders 2 2117 Springs (bag 100) 1 1118 Ticker tape machine 1 1119 45 record 2 2

Photo Credits

All photos by the Collyer’s team unless otherwise credited:

EXP 11• Leopard in Tree; U.S. Fish and Wildlife ServiceEXP 47• Ultrasound Scan; Sam PullaraEXP 56• Mirage in the Mojave Desert; Mila ZinkovaEXP 57• Very Large Array, New Mexico; Wikipedia user HajorEXP 57• Bigfin Reef Squid; Nick HobgoodEXP 59• Thermogram of a Small Dog; NASA/IPACEXP 59• Mobile Phone; Jon JordanEXP 59• X-Ray of Anna Röntgen; Wilhelm RöntgenEXP 67• Hubble Ultra Deep Field; NASA and the European Space AgencyEXP 68• Tarantula Nebula; The Hubble Heritage TeamEXP 68• Eagle Nebula; NASA, Jeff Hester, and Paul Scowen (Arizona State University)

Build Your Own Paper Plane (EXP 23)

This paper aeroplane design is called the Arrow. It is one of the most popular and recognisable planes out there, and with a little careful fold-ing it flies brilliantly!

Thi paper aeroplane design lled the Arrow. It is

one of the most popular and recognisable planes out there, and with a little careful fold-ing it flies brilliantly!

1This is caone o

1Start with a plain piece of A4 paper. Fold it in half along its length and flatten it out again. This way you can see a crease where the middle of the paper is.

St t with a plain piece of A4 er. Fold it in half along

its length and flatten it out again. This way you can see a crease where the middle of the paper is.

2Start papeits le

2

Fold the two top cor-ners of the paper down towards the crease to form two folded triangles.

F ld the two top cor- of the paper down

towards the crease to form two folded triangles.

3Fold ners towa

3

Now fold the top edges of that shape towards the crease again, so that you have this shape:

N w fold the top edges hat shape towards the

crease again, so that you have this shape:

5Now of thcreas

5

Fold the top edges of those triangles down towards the crease again so that you have this shape:

F ld the top edges hose triangles

down towards the crease again so that you have this shape:

4Foldof thdown

4

Fold the entire piece of paper in half now, along the original crease you made. Fold it so that these pieces are on the outside.

F ld the entire piece of er in half now, along

the original crease you made. Fold it so that these pieces are on the outside.

6Fold papethe o

6

Now when you lay the plane down you will see that it unfolds itself so that the back of the plane forms an “M” shape, like in this picture.

N w when you lay the plane down you see that it unfolds itself so that the

back of the plane forms an “M” shape, like in this picture.

7Now will back

7

That middle bit of the “M” is the bit you need to hold when you are throw-ing the plane.

Th t middle bit of the “M” is the bit need to hold when you are throw-

ing the plane.8

That you ning t

8

Throw the plane and watch it go! If it doesn’t fly straight away, you need to bend the back of the wings a bit to help it go straight. If it dives, bend the wings up gently. If it shoots straight up and then crashes, bend the back f the wings down a bit.

Th ow the plane and watch it go! If esn’t fly straight away, you need

to bend the back of the wings a bit to help it go straight. If it dives, bend the wings up gently. If it shoots straight up and then crashes, bend the back f the wings down a bit.

9Throit doto be

9

Experience Your Blind Spot (EXP 51)

For more information about IOP’s education projects in Africa and for access to other educational resources, contact:

Dr Dipali Bhatt-Chauhan International relations manager

Institute of Physics76 Portland Place, London W1B 1NT, UKTel +44(0)20 7470 4800Fax +44 (0)20 7470 4848E-mail [email protected]

www.iop.org/internationalwww.iopblog.org Registered charity number: 293851Charity registered in Scotland: SC040092

For more information about IOP’s education projects in Africa and for access to other educational resources, contact:

Dr Dipali Bhatt-Chauhan International relations manager

Institute of Physics76 Portland Place, London W1B 1NT, UKTel +44(0)20 7470 4800Fax +44 (0)20 7470 4848E-mail [email protected]

www.iop.org/internationalwww.iopblog.org Registered charity number: 293851Charity registered in Scotland: SC040092

Teaching Practical Physics Anywhere

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Transcript of Teaching Practical Physics Anywhere