Duncanrig Secondary School · Web viewDuncanrig Secondary School East Kilbride S2 Physics Elective...

Duncanrig Secondary SchoolEast Kilbride

S2 Physics Elective

Light and Sound

Activity Booklet

S2 Physics Elective Light and Sound

INSTRUCTIONS: Always put today’s date and copy each HEADING carefully.

A good scientist always dates their work. Your jotter will form a complete set of notes on Light and Sound. It is important that you keep a useful record of work in your jotter. Full sentence answers are required for questions and experiments should be fully written up with a conclusion checked by your teacher. If you are off it is your responsibility to ‘catch up’. Speak to your teacher or friends to find out what you missed and get a copy. Homework will be issued throughout the course. It should be completed on time. Use your homework diary to help you manage your homework exercises.

Symbols used in this booklet:

Copy

The little pencil symbol means that you copy the passage neatly into your Physics Jotter. It is important that the Copy Passages are copied accurately since the content may appear in the End of Unit Test.

Read

The little book symbol means that you must read the passage carefully so you can extract the required information and so that knowledge is gained for the test.

What to do

This little symbol means you must collect apparatus and carry out an experiment OR follow instructions in an activity. Remember, apparatus may be delicate and costly and should be treated as such. Please return all apparatus to its appropriate place of storage.

Questions Answer in full sentences

Page 1


This little question symbol means that there are some questions to be answered as best as you can. If you are unsure of an answer, your teacher may help or you can find out the answer from other sources like a text book or internet. A full sentence answer means you can tell what the question is from reading the answer.

More to do

The plus sign means that, if you have the time, there is more work that can be done.

Watch a video

This symbol means that your teacher may show you a short video clip.

See something on the internet

Your teacher may show you something on the internet to help your understanding.

Page 2


HEADING Activity 1 Refraction

Read

The speed of light in air/vacuum is 300 000 000 m/s. As light passes from air through another transparent* material it slows down e.g. the material could be water, glass, Perspex etc. How much the speed of light slows down by depends on the material it passes through. This change in speed as the light passes from one medium (material) to another is called refraction. All waves have the ability to refract. You will have the opportunity to direct light through transparent shapes made of Perspex in order to see the effect refraction can have on the direction of light.*Transparent means that light can pass through.

What to do

1. Visit the five stations as instructed by your teacher.2. Complete the worksheet provided. Use the station instruction cards to

help.


1. What happened to the direction of the ray of light when striking an air/Perspex boundary at 90°?

2. What happened to the direction of the ray of light when striking an air/Perspex boundary not at 90°?

Copy

Refraction is the change in speed of light as it travels from one medium to another. If the incident angle is not 90°, there is a change of direction.

Page 3


HEADING Activity 2 Measuring Angles of Incidence

Read

The next activity requires you to measure angles with a protractor. It’s important that you learn this skill. Let’s get some practice.

What to do

Use you protractor to measure the following incident angles. Remember to measure

from the normal (the dotted line at 90° to the boundary where the ray strikes).

IncidentAngle

Normal

Right angle

a b c

Ray

Boundary

d e f

Page 4


Copy

The normal is drawn at 90° to the boundary where the ray strikes. This is an imaginary line. All angles are measured from this line.

Page 5


HEADING Activity 3 Comparing Angles

Read

You will have noticed in Activity 1 that during refraction a change in direction can occur. This activity allows you to investigate how the incident angle compares with the refraction angle for light traveling from Perspex to air. If you correctly follow all the instructions below you will end up with a complete report consisting of an aim, hypothesis, diagram, method, results, and conclusion. Make sure you have all of these sections in your report.

What to do

1. Write a suitable aim for this experiment.2. Write a hypothesis (this is an educated guess about what you think will

happen – how do you think the refraction angle will compare with the incident angle? Use the word(s) smaller/larger/stays the same).

3. Copy the diagram below:

4. Read the following instructions and use them to help write a suitable method.

5. Mark the position of the prism, normal, and 10° incident angle ray on your paper. Set up the apparatus as in the diagram.

6. Direct a single ray of light from the ray box along the 10° incident angle ray.

7. Mark where the refracted ray leaves the Perspex semi-circular prism.8. Repeat for incident angles of 20° and 30°; use a different pencil colour for

each.9. Measure the refraction angles with a protractor and record them in a

suitable results table along with the incident angles.10. Write a conclusion for your experiment (look back at your aim and

results).

Page 6

10° incident angle

Ray box

Printer paperSemi-circular prism


HEADING Activity 4 Convex Lenses

Read

During Activity 1 you saw that convex lenses converge rays to the same point called the focus. The distance from the centre of the lens to the focal point is called the focal length. The ability of this type of lens to converge light means it can be used in variety of applications. This activity involves investigating the effect a convex lens has on light coming from an object placed at different distances from the lens. The object will be placed between the lens and the focal length (object distance < f), between the focal length and two times the focal length (f < object distance < 2f), and beyond two times the focal length (object distance > 2f).

What to do

1. Copy the table below.

Object distance Image Size Image Orientation Real OR Imaginary

< f> f but < 2f

> 2f2. Use the terminology word box to complete the table as your teacher demonstrates this

experiment.

Terminology Word BoxMagnified

Increased in size.

Diminished

Decreased in size.

Upright Image is the same way up as the object.Inverted Image is upside down compared to the object.Laterally Inverted

Flipped horizontally.

Real Image can be projected into a screen.Virtual Image cannot be projected onto a screen, can only be seen by the

eye.3. Draw the object and corresponding image for each of the three situations

shown. Make sure that you consider the size and orientation of your image.

Page 7

Focus or focal point


4. You have seen that a convex lens can make the image larger or smaller; it can even turn it upside down, flip it horizontally or project it onto a screen. Can you think of any applications of convex lenses where they have been used because it can do some of these things?

More to do

Produce an image of the window onto screen and use the lens to look at some text.

What to do

1. Collect a convex lens with focal length 10cm.2. Tape a sheet of printer paper onto the door of one of the wall cupboards.3. Hold a convex lens parallel to the paper about 5cm away. Make sure the

hold the lens by the edges so as not to block the light coming through.4. Move the lens closer/further away from the paper until you see a sharp

image of the window on the screen.5. Now look at the text on this booklet through the lens. Hold the lens about

1cm away and move it back to a few cm away.


1. What do you notice about the image of the window on the screen? If there is a letter F on the window it will help you here.

2. What did you notice about the text on the booklet when viewed through a lens?

3. Have you confirmed you findings from the last experiment? Explain.

Page 8


HEADING Activity 5 The Structure of the Human Eye

Copy

The human eye is round in shape and is about 24mm in diameter. The eye is used to detect light energy and works with the brain to provide us with sight.The eye and brain work together to convert light waves into a sensation we call vision.

What to do

Using the information above, collect and label a copy of the EYE DIAGRAM.Your diagram should be glued in to your jotter.

Questions Answer in sentences

1. What is detected by the human eye?2. Which part of the body works with the eye to provide vision?3. What is the approximate diameter of the human eye in centimetres?

Page 9

cornea

eye muscles toswivel the eye

iris

lens

retina

optic nerve

pupil blind spot

yellow spot(fovea)

ciliary muscles

EYE DIAGRAM


HEADING Activity 6 How the Eye Works

Read the information below

How the eye works

Eye muscles are used to swivel the eye left or right, up or down. Light enters the eye through a clear protective covering called the cornea. The cornea is curved and refracts light rays to a focus. The lens finely adjusts the focus position depending on the object’s distance to ensure that the focus lands on the retina. The retina is a light sensitive screen at the back of the eye made up of light sensitive cells; this is where the image forms. The ciliary muscles control the curve of the convex lens inside the eye. When the focus falls on the yellow spot (fovea) fine detail like small print can be seen clearly. The pupil is a hole in the eye that lets a certain amount of light in. The size of the pupil is controlled by the coloured part of the eye called the iris. The optic nerve that leaves the back of the eye transmits electrical signals to the brain. The blind spot is where the optic nerve leaves the retina; there are no light sensitive cells here.

What to do

1. Collect the ‘How the Eye Works’ matching cards.2. With your partner match the part of the eye with the corresponding

description.3. Check your answers with your teacher.4. Copy the information into your jotter.

Page 10


HEADING Activity 7 Accommodation

Read

In the previous activity you read how the cornea and the lens both cause refraction of the light entering the eye. However, we want to concentrate this activity on the lens as it can change its thickness. This change in thickness is dependent on the distance of object it is trying to focus on.

Thin lens Thick lens

What to do

Your task is to find out if the lens is thick or thin when the object is near or far from the lens. If you correctly follow all the instructions below you will end up with a complete report consisting of an aim, hypothesis, diagram, method, results, and conclusion. Make sure you have all of these sections in your report.1. Write a suitable aim for this experiment.2. Write a hypothesis (this is an educated guess about what you think the

result will be).3. Copy the diagram below:

4. Read the following instructions and use them to help write a suitable method.

Page 11

12 volt lamp (object)

30 cmwhite screen (retina)thin convex

lens

metre stick


5. Set up the apparatus as in the diagram.6. Keep the distance from the lens to the screen fixed at 30 cm.7. Bring the lamp towards the lens until a sharp image of the lamp appears

on the screen.8. Measure the distance from the lamp (object) to the lens.9. Replace the thin lens with the thick lens and repeat steps 5 - 7.10. Compare the two distances measured and consider which one is

nearer/further from the lens.11. Put a tick in the appropriate box of a suitable results table like the one

below.

Distance from Lamp to LensLens Shape Near FarThin ConvexThick Convex

12. Write a conclusion for your experiment. Use the passage in the box below to help you if you are unsure.

When focusing on nearby objects the eye lens is _____________ . When focusing on far away objects the eye lens is _____________ .

Copy

The ability of the eye lens to change shape in order to focus on objects at different distances is called ACCOMMODATION.

What to do

1. Collect and complete the Accommodation Diagram and glue it into your jotter.

2. Get your teacher to check your work.

Page 12


HEADING Activity 8 Eye Defects

Read

There are two eye defects that we will discuss in this topic – long-sightedness and short-sightedness. People who are longsighted can only focus on objects which are far away but nearby objects appear blurry. People who are short-sighted can only focus on objects which are nearby but objects which are far away

appear blurry. It is important to note that light from far away objects is considered parallel and light

from nearby objects is considered diverging.

Parallel light from a distant object Diverging light from a nearby objectTherefore people who are longsighted can accommodate parallel rays and people who are short-sighted can accommodate diverging rays. The focus always lands on the retina.

We can use lenses in the form of spectacles or contact lenses to correct these eye defects. There are two lenses to choose from - convex and concave.

Page 13


Can you remember the effect these lenses have on light? The words converging and diverging may give you a clue.

What to do

1. Collect a ray box, convex lens and concave lens.2. Observe again the effect a convex lens has on three parallel rays of light.3. Observe again the effect a concave lens has on three parallel rays of light.4. See if you can work out how to make the diverging rays from the concave

lens parallel again.5. Copy and complete the diagrams below. Use a ruler.

Read

We have enough information now that we should be able to identify which lens corrects which eye defect. In the next activity you will put all the evidence together to see if you can work out which lens, convex or concave, can correct which eye defect.

Page 14


HEADING Activity 9 Eye Defects – Which Lens?

What to do

Look at the diagram above. It shows someone who is short-sighted looking at an object far away. They are unable to focus the rays on the retina (the focus is short of the retina).


1. What type of rays can a shortsighted person accommodate (bring to a focus on the retina)?

2. What effect will a concave lens have on parallel rays of light?3. Therefore what lens could you use to correct this eye defect?

Look at the diagram to the right. It shows someone who is longsighted looking at an object nearby. They are unable to focus the rays on the retina (the focus is long of the retina).


4. What type of rays can a longsighted person accommodate (bring to a focus on the retina)?

5. What effect will a convex lens have on diverging rays of light?6. Therefore what lens could you use to correct this eye defect?

What to do

Watch the teacher demonstrations of the eye models.

Page 15


HEADING Activity 10 Eye Defects – ConsolidationLong-sighted Short-sighted

People who are long-sighted can focus on objects far away

People who are short-sighted can focus on objects close up

When people who are long-sighted try to look at an object close up the lens of their eye cannot adjust enough to focus the rays onto the retina of the eye. The rays focus behind the retina, like this:

When people who are short-sighted try to look at an object far away the lens of their eye cannot adjust enough to focus the rays onto the retina of the eye. The rays focus in front of the retina, like this:

This means that they see an unfocused (blurry) image.

This means that they see an unfocused (blurry) image.

To correct this problem we need a lens, which will converge the rays before they enter the eye – a convex lens will do this, like this:

To correct this problem we need a lens, which will diverge the rays before they enter the eye – a concave lens will do this, like this:

A convex lens can be used to correct long-sightedness.

A concave lens can be used to correct short-sightedness.


1. In relation to the retina, where do the rays focus for some who is(i) short-sighted, for a distant object? (ii) long-sighted, for a nearby object?

2. Which lens corrects short-sightedness and which corrects long-sightedness?

3. Without correction, what type of image do people with eye defects see?

More to doCollect the eye defects statement cards and identify each statement as long or short sighted.

Page 16


HEADING Activity 11 Controlling Light Entering the Eye

Read

The pupil and the iris

Too much light can damage the retina. The eye can experience intense pain in very bright light and the retina can be permanently damaged.The iris controls the size of the pupil. The pupil is a hole in the eye that lets in light.The pupil then allows the required amount of light to enter the eye.

Copy and label this diagram of the front view of the eye.

What to do

Work with a partner.Your partner should cover their left eye for a minute so that it is darkness.Quickly, observe the size of the pupil of your partner’s left eye.Now, carefully shine a torch into your partner’s left eye.Notice what happens to the size of the pupil. Swap over and repeat this experiment.

Copy and complete the diagrams below.Draw in the pupil in both diagrams. The pupil should be the

appropriate size.

Page 17

The eye in darkness

The pupil is small / large

The eye in bright light

The pupil is small / large

Front view of the eye

iristhe coloured part

pupilwhite of the eye

(sclera)

tear duct


HEADING Activity 12 The Blind Spot

Read

The place where the optic nerve meets the retina is called the blind spot.There are no light sensitive cells here so no light rays can be detected.Each human eye has a blind spot. You can locate your own blind spot.

To find the blind spot in your right eye.

What to do

Cover your left eye. It is the blind spot in the right eye that will be found.Position the magician at arms length directly in front of your right eye.Stare at the magician. Do not look at the dog-just notice that the dog is there.Move this page slowly towards your right eye staring at the magician.At one point the dog should disappear.Bring this page further towards your right eye and the dog should then reappear.

Copy the passage below and copy or trace the blind spot diagram

When the image of the dog disappears, light rays from the dog are falling on the blind spot of the right eye. This is a small area where the optic nerve joins the retina. The blind spot is not sensitive to light.The image of the dog cannot be detected

Page 18

blind spot(no image of

dog)

optic nerveto brain

retina

right eyeball

light ray from magician

light ray from dogpupil

yellow spot (fovea)

BLIND SPOT DIAGRAM


HEADING Activity 13 The Mysterious Floating Finger

Read

The mysterious floating finger is an example of an optical illusion.An optical illusion is a false visual impression, in other words, you can see something that is not really there. For example, an oasis in the desert.You may see something that is not actually present like a mysterious floating finger.

What to do

Place the index fingers from both your hands about 30 cm in front of your face.Position your fingers so they are just touching.

Focus your eyes

You should then see a mysterious floating finger.Keep trying this experiment until it works. When you see the mysterious finger separated your fingers by about 1 cm then it should appear like the one below.


1. What is meant by an optical illusion?2. Explain why you think the illusion of the mysterious floating finger works.3. Suggest another example of an optical illusion.

Page 19


HEADING Activity 14 The Escaped Prisoner

See if you can put the escaped prisoner back into the jail.

What to do

Place a white card upright on the dotted line on the sketch below.Look down at the pictures close-up with both eyes close to the edge of the card so that each eye only sees one picture.The prisoner should appear back in jail.

Read

The escaped prisoner is another example of an optical illusion.Each eye sees only one picture but the brain can place the two pictures together.The illusion is that the prisoner is in the jail. You can see from the diagram above that the prisoner is outside the jail.


1. Explain in your own words how the prisoner appears in jail.2. Which part of the body works with the eyes to create this illusion?

More to doDesign and draw in your jotter an illusion similar to this one of your own choice.For example: a car that drives into a garage or a dog going into its kennel.

Page 20


HEADING Activity 15 The Pinhole Camera

Copy this diagram

What to do

1. Carefully use a pin to make one pinhole in the middle of the black paper.

2. Point the camera at the lamp with the Letter F as in the diagram.3. Look at the image of the letter F on the clear paper screen.

Copy and choose a suitable answer from your observations:

The image of the letter F seen with a small pinhole isdim / bright; sharp / not sharp;up the right way / upside down; reversed / not reversed.

1. Now make the pinhole much wider by placing a pencil through the pinhole.

2. Now look at the image of the letter F on the clear paper screen.

Copy and choose a suitable answer from your observations:

The image of the letter F seen with a large pinhole isdim / bright; sharp / not sharp;up the right way / upside down; reversed / not reversed.

1. Now place a convex lens in front of the large pinhole.2. Look again at the image of the letter F on the clear paper screen.

Copy and choose a suitable answer from your observations:The image of the letter F seen with a convex lens in front of a large

pinhole isdim / bright; sharp / not sharp;up the right way / upside down; reversed / not reversed.

Page 21

letter Fover 12 volt lamp

pinhole camera

screenpinhole in black paper

F LOOK FOR IMAGE OF THE LETTER F ON THE SCREEN


HEADING Activity 16 How the Pinhole Camera Works

See something on the internet

Your teacher may show you an animation on the internet to help explain the image formed on the screen of the pinhole camera.http://www.curriculumbits.com/prodimages/details/physics/how-pinhole-camera-work.html

Copy this diagram

Read

When the image of a letter F is seen on the screen of a pinhole camera the image is of a letter F upside down and reversed. This is because light travels in straight lines.If the image on the screen is dull and blurred, the image can be made brighter and sharper by:

1. Making the pinhole larger-this allows more light through the pinhole.

2. Putting a lens in front of the pinhole-this makes the image sharper.

The First Pinhole Camera Photographs

Sir David Brewster, a Scottish scientist was one of the first to use the new light- sensitive film to make pinhole camera photographs in the 1850s. Sir David Brewster also was first to name this type of camera a "pinhole camera".


1. State two differences between the image (what is seen on the screen) and the object (what you are looking at) when using a pinhole camera.

Page 22

This is the object-a letter F

This is the image of the object.Notice the letter Fis upside-down and reversed

These are the light rays. Notice that light travels in straight lines

This is the pinhole camera

This is the screen

This is the pinhole

http://www.rleggat.com/photohistory/history/brewster.htm


2. When using a pinhole camera to look at a distant tree, the image is bright but not very sharp. State what you must do to make the image sharper.

3. Who was the first scientist to name the pinhole camera?

Page 23


HEADING Activity 17 The Camera and the Eye

Read

Sharp images are formed in a camera by the refraction of light rays. Light is focused in a camera in a similar way it is focused in the eye. The pinhole camera works in a similar way to the human eye. A camera is a dark box. The hole in a camera is called the aperture and lets light in just like the pupil of the eye. A camera lens is a glass version of the transparent lens inside the eye. The shutter on a camera is like your eyelids-light enters a camera only when the shutter is opened.The upside down and reversed image formed in a camera is formed in the same way as it is on the retina of the eye.The main difference between a traditional film camera and a digital camera is the way the image is captured. Instead of a roll of film, digital cameras use a device called an image sensor which is a silicon chip the size of a fingernail. On its surface are millions of pixels each sensitive to light. When a digital photo is taken, the light from each pixel is converted to a digital number. The series of numbers can be used to reconstruct the image by setting the colour and brightness of matching pixels on the little viewing screen on the camera or on a printed picture. Digital cameras still consist of a lens, a dark box and digital film.

Questions Answer in sentences1. What is meant by the refraction of light? (Look back at the first

activity if you are unsure).2. State the name of the hole that lets in the light in a camera.3. What is the main difference between a film camera and a digital camera?4. What happens to the light when a digital photo is taken?5. What are the three main parts of a digital camera?6. Which one part of your answer to Q5 is also found in the human eye?

Page 24


HEADING Activity 18 The Refracting Telescope

Read

A telescope is used to collect and focus light. Normally the light has come from a distant object so there is also a need for the telescope to magnify. A simple refracting telescope is made from a light tight tube, an objective lens and an eye piece lens. You will get the opportunity later to make a simple refracting telescope. However, first you need to learn the skill of measuring the focal length of the lens to help you make your telescope.

What to do

During Activity 4 you produced an image of the window onto a screen. You are going to follow the same instructions again but with a few more added so you can measure the principal focal length of the lenses you will use for making your telescope.1. Collect two different thicknesses of convex lenses.2. Tape a sheet of printer paper onto the door of one of the wall cupboards.3. Hold a convex lens parallel to the paper about 5cm away. Make sure the

hold the lens by the edges so as not to block the light coming through.4. Move the lens closer/further away from the paper until you see a sharp

image on the screen.5. With the help of your partner measure the distance from the screen to the

centre of the lens using a ruler. This distance is the focal length. 6. Record this information in a table like this.

Lens Measured Focal Length (m)

Actual Focal Length (m)

ThinThick

7. Check the actual values of focal length with your teacher and complete the table.

HEADING Activity 19 Building a Simple Refracting Telescope

ReadPage 25


From Activity 18, you know which one of the convex lenses has the longer and shorter focal length. With this information you can start to build your refracting telescope.

What to do

You will need the following apparatus:Convex lens with long focal length Convex lens with short focal

lengthBlu-tack

Cardboard tube with narrower diameter

Cardboard tube with thicker diameter

Put the apparatus together as in the diagram below:

The objective lens should be the lens with the longer focal length. The eyepiece lens should be the one with the shorter focal length. The lenses should be held in place by the Blu-tack. Form a complete seal. Be careful to make sure they are secure before you use the telescope. In order to focus your simple telescope on a distant object slide the inner tube forward and back until you see a sharp image.

More to do

Calculate the magnification of your telescope from the formula below.Magnification = (Focal Length of Objective Lens) / (Focal Length of Eyepiece

Lens)Use the actual values provided by your teacher in the last activity

Page 26

Objective Lens

LightFocal point Narrower tube

Thicker tube

Eyepiece Lens


HEADING Activity 20 The Refracting Telescope - Consolidation

Read

Refracting telescopes consist of a light tight tube. At one end of the tube is an objective lens and at the opposite end there is an eyepiece lens. To focus on objects at different distances the length of the tube can be changed. Light from a distant star or planet is collected by the objective lens, the rays are refracted, and an image is formed at the point of focus at the lower end of the tube. This image acts as an object for the eyepiece lens which magnifies the bright image. To obtain a brighter image more light from the distant object needs to be collected. This can be done by making the diameter of the objective lens larger.


1. Name the three main parts that make up a refracting telescope.2. Why is there a need to adjust the length of the light tight tube?3. What is the function of the objective lens?4. What happens to the light collected by the objective lens?5. What is the function of the eyepiece lens?6. How can a brighter image be obtained?7. What changes would you need to make to the telescope design to obtain a

more magnified image? (It may help you to look back at the ‘More to do’ section in the last activity).

More to do

Copy or trace the diagram of the refracting telescope from the previous activity.

Page 27


HEADING Activity 21 The Structure of the Human Ear

Read

The human ear has two functions: hearing and balance. The ear has three main parts: the outer, middle and inner ear. The outer ear is the part you can see and opens into the ear canal. The eardrum separates the ear canal from the middle ear. Three small bones in the middle ear transmit sound vibrations to the inner ear. The inner ear contains the cochlea which converts the vibrations into electrical signals. These electrical signals pass along the nerve to the brain. The semicircular canals in the ear have nothing to do with hearing. They are required for balance.

What to do

Collect a copy of the EAR DIAGRAM. Use the information above to complete it. Glue it into your jotter.


1. What is detected by the human ear?2. What is the function of the three small bones in the middle ear?3. Which part of the ear converts vibrations into electrical signals?

Page 28

outer ear

ear drum

small bones

cochlea

nervetothe brain

semicircular canals

ear canalouter lobe

EAR DIAGRAM


HEADING Activity 22 Making Sound

Copy underlined

Sound is a form of energy. The ear is used to detect sound energy and works with the brain to provide us with hearing. The ear and brain work together to convert sound waves into a sensation we call hearing.

What to do

1. Tap the tuning fork on the cork. 2. Place the stem of the tuning fork

on the wooden bench. 3. Listen to the musical note produced.

4. Tap the tuning fork again and rotate the tuning fork near to your ear.

5. Listen carefully to the sound made by the tuning fork.

6. Tap the tuning fork again on the cork and gently place one of the prongs into the water in a Petri dish.

7. Observe what happens to the water surface.

Copy underlineThe tuning fork caused the water to move. When an object is making a

sound it is moving (vibrating).

Page 29

stem prongs


HEADING Activity 23 Sound Vibrations

ReadSound is what is produced when an object such as a tuning fork is caused to move or vibrate. All sounds are caused by vibrations. Sound is heard when movements inside the ear sends electrical impulses to the brain.The pitch of a sound or musical note is a measure of how high or how low it is.A high note has a high pitch. A low note has a low pitch.

What to do

1. Twang the end of a ruler. 2. Listen to the sound that is made.

Observe that the ruler has to move every time a sound is made.

3. Listen to the sounds made when the vibrating end of the ruler is long and again when it is short.

4. Compare the pitch of a long vibrating ruler and a short vibrating ruler.5. Twang the ruler soft and then hard. Do not change its length.6. Compare the pitch of a vibrating ruler twanged hard and then

twanged soft.

Read

When an object vibrates, sound is given out. Unless the object vibrates, no sound is given out. A long ruler vibrates at a slower rate than a short ruler. A long ruler gives out a low pitch sound and a short ruler a higher pitch sound.The faster an object vibrates then the higher the pitch is the sound produced.Pitch and frequency are related. Frequency is the number of vibrations per second. The lower the frequency the lower the pitch and the higher the pitch the higher the frequency. The human ear cannot detect sounds which have a very high pitch.A dog whistle can be heard by a dog but not by a person because a dog can detect sounds of a much higher pitch than a person.


1. What is meant by the frequency of a sound?2. Explain clearly the connection between pitch and frequency.3. Explain why a dog whistle cannot be heard by a person.

Page 30


HEADING Activity 24 Travelling Sound

Copy

Sound can easily travel through the air which is a gas. Sound can also travel through other materials like solids and liquids.

What to do

1. Place your ear gently on the bench.2. Place your finger in your other ear so you

can only hear sound travelling through the bench.

3. Listen to your partner gently scratching the bench

4. Now listen to your partner gently scratching the bench but listen to the sound coming through the air.

5. Compare the level of sound reaching your ear.

Copy

Sound is transmitted better by wood which is a solid than air which is a gas.

More to doWork on your own. Place a stopclock ticking on the bench and stand 1 metre away.Listen for the ticking of the clock. Listen carefully to the loudness of the sound.Now place a wooden metre stick carefully between the stopclock and your ear.

Note the new level of the sound.


1. Which material, air or wood transmits sound better?2. Explain clearly why you think sound is transmitted by some materials

better than others.

Page 31

wooden metre stickwooden bench

ticking clock

carefully place metre stickat your ear


HEADING Activity 25 Loudness (amplitude) of a Sound

Copy

The sounds that we hear like speech or music are different because two things about a sound can change:

1. The loudness (amplitude) of the sound.2. The frequency (pitch) of the sound.

What to do to investigate loudness (amplitude)

Set up this circuit to investigate the loudness (amplitude) of a sound:

1. Adjust the frequency of the signal generator so that the sound produced has a frequency of 4000 hertz Hz.

2. Adjust the oscilloscope controls so that a signal like the one on the right is on the screen of the oscilloscope:

3. Vary the output control. This will increase and decrease the loudness (amplitude) of the sound. The sound should be louder and quieter.On TV sets and radios, the volume control adjusts the loudness (amplitude).

Copy this note and trace or copy the diagrams below

When the loudness (amplitude) of a sound increases, the height (amplitude) of the wave increases. There is no change to the frequency (pitch).

HEADING Activity 26 Frequency (pitch) of a Sound

Read

Page 32

Signal Generator LoudspeakerCathode RayOscilloscope

no sound LOUD SOUNDquiet sound


The sounds that we hear like speech or music are different because two things about a sound can change:

1. The loudness (amplitude) of the sound.2. The frequency (pitch) of the sound.

What to do to investigate frequency (pitch)

Set up this circuit to investigate the frequency (pitch) of a sound:

1. Adjust the frequency of the signal generator so that the sound produced has a frequency of 4000 hertz Hz.

2. Adjust the oscilloscope controls so that a signal like the one on the right is on the screen of the oscilloscope:

3. Vary the frequency control. This will increase and decrease the frequency (pitch) of the sound. The sound should be higher and lower in pitch.

Copy this note and trace or copy the diagrams below

When the frequency (pitch) of a sound increases, more waves are seen on the screen.There is no change to the loudness (amplitude).

Page 33

Signal Generator LoudspeakerCathode RayOscilloscope

original sound frequency lower frequency higher


HEADING Activity 27 Sound from a Stretched String

Read

Some musical instruments like the guitar and violin use a vibrating stretched string to make pleasant sounds. The sounds produced can vary in loudness (amplitude) and frequency (pitch). The frets on a guitar can be used to make the length of the string longer and shorter. The tightening key on a guitar string can be used to tighten the string without changing its length.

What to do

Use the guitar to complete the following table (use the word increased, decreased or stays the same.

Adjustment Loudness (amplitude)

Frequency

Pluck HarderSofter

Length of string LongShort

Tightness of string

TightLoose

Use the information from your table to complete the following sentences.

PluckWhen a stretched string is plucked harder, the loudness (amplitude) of the sound produced ___________________ . The frequency (pitch) of the ___________________ .

Length of StringWhen a stretched string is shortened, the frequency (pitch) of the sound produced ___________________ .The loudness (amplitude) of the note ___________________ .

Tightness of StringWhen a stretched string is tightened, the frequency (pitch) of the sound produced ___________________ .The loudness (amplitude) of the note ___________________ .

Page 34


HEADING Activity 28 Sound Engineering Project

Read

During this project you will be recording and manipulating sound signals. One of the sound signals will be a recording of your voice, the other will be a music file. You can use one of your own music files or something from the internet or shared area. You will need to ‘ok’ the music with you teacher. It is essential that the version of music you are using is the radio edit to ensure that the language in it is suitable for school use. However, it may make more sense to choose an instrumental version. The software you will be using is called ‘Audacity’ and is installed on all the PCs in the school. It may be helpful to install this software on your PC at home. It can be downloaded for free from http://audacity.sourceforge.net/. Make sure you download version 1.2.6 as this is the same as the version that is installed at school. It is likely that you will need to spend some of your own time completing this project.

What to do

Your teacher will show you four PowerPoint presentations. Each presentation will consist of four slides with pictures on them. The pictures relate to work completed during the course. Once you have picked one of the presentations to work with, it is you job to write a narrative to go along with the slides, record this narrative, add some backing music and finally link what you have recorded with the PowerPoint. Instructions on how to do this are on the acetate provided.1. Write a narrative for each slide in the presentation you have picked.2. Check your work with your teacher before proceeding.3. Collect ‘Audacity S2 Sound Engineering Project’ instruction acetate.4. Ensure you check in with your teacher at each of the check points before

you move on to the next stage.

Page 35

http://audacity.sourceforge.net/


HEADING Activity 29 VIDEO: Science in Action Tape 22

Copy the following leaving two lines between each question for your answer

Light Questions on Light

1. Why do the eyes of the cat glow in the dark?2. Why is the yellow jacket easier to see than the red jacket? 3. What happens to the light reflected from the yellow jacket? (retro

reflecting)4. Name another situation in which retro reflecting material is used. 5. Why is the illumi-vest visible?6. Why does a beam of light become visible? 7. What type of light is being fired into space? 8. What is the light being aimed at?9. How far must this light travel? 10. How long does the journey take? 11. At what speed does light travel?12. What causes the moon to shine?13. How many stars are in the galaxy?14. How long does light take to travel from the nearest star?15. What is the name of the type of telescope that we see in the video?

More to do

Apparatus required: a pen or pencil; a clean glass rodIn little BLOCK CAPITALS, write down the two words CARBON DIOXIDE in your jotter.View your writing through a glass rod and write down an explanation of what you see.

Page 36


HEADING Activity 30 VIDEO: Your Living Body Tape 30

Copy the following leaving two lines between each question for your answer

Looking and Listening

Questions on Looking1. In which two ways do we find out about the world around

us?2. Name the transparent surface at the front of the eye. 3. In what way is an eye lens different from a camera lens?4. Why does the eye lens need to change shape? 5. Describe the effect of a bright light on the iris of the eye.6. Is the iris in front or behind the lens of the eye? 7. Name the light-sensitive surface on the inside of the eye. 8. Where in the body is the optic nerve?9. What name is given to the light sensitive cells which detect movement? 10. Name the cells which allow us to detect colour. 11. Red and green mix together to give which colour?

Questions on Listening1. How are sound waves described?2. Describe the look of an eardrum.3. Where in the ear are the small bones located? 4. What do the tiny hairs do when they detect sound? 5. What is the effect of a loud sound on the tiny hairs? 6. What method can the girl employ to avoid

becoming dizzy?7. Who uses this method to avoid becoming dizzy?

END OF ACTIVITY BOOKLET - Light and Sound

Page 37

Duncanrig Secondary School · Web viewDuncanrig Secondary School East Kilbride S2 Physics Elective...

Documents

Transcript of Duncanrig Secondary School · Web viewDuncanrig Secondary School East Kilbride S2 Physics Elective...