SCIENCE -...

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SCIENCE: YEAR 7 REVISION GUIDE—BIOLOGY SECTION

Science Department

This Revision Guide will be generated as the year progresses. Each topic is

covered with both ‘key fact’ sheets, a question sheet and a suggested revision

method.

The question sheet is designed to test your revision of the key facts and see if

the information has sunk in. Just answering the questions is not an effective

revision method.

You will be given a set of sheets for each topic as you cover them in lessons.

The revision sheets will help you to revise for the end of unit test and your

school entrance exams at the end of year 8.

You will be given one hard copy to store in this folder but replacements can

be found online in the Student and Parent Portal section of the school

website. You are allowed to print as many copies as you like for your own

use.

We hope that they will be useful.

Good Luck

The Science Department

Photosynthesis

The process by which plants make their own food (glucose) using light energy.

Word Equation =

Necessary Conditions = Light and Chlorophyll (Chemical used to convert light energy)

Leaves are main area in which photosynthesis happens. Why?

Proving Photosynthesis has occurred

Test for starch – Plants store glucose as starch because it is insoluble. If a plant has been

photosynthesising it will have produced starch.

Proving Light is necessary for Photosynthesis

Destarch plant by placing in dark for 24 hours. Expose half of a leaf to light and cover half with pa-

per. Test for starch 24 hours later and observe that area exposed to light turns black (starch present)

and area covered remains brown (starch not present).

Proving Carbon Dioxide is necessary for Photosynthesis

Destarch plant by placing in dark for 24 hours. Cover one leaf in plastic

bag containing soda-lime (absorbs Carbon Dioxide from atmosphere).

Test for starch after 24 hours. Brown colour should indicate lack of

photosynthesis.

Carbon Dioxide + Water Glucose + Oxygen

Test for starch:

1. Boil leaf in water to remove waxy cuticle

(to allow Iodine Solution to penetrate leaf)

2. Place leaf in boiling ethanol

(To dissolve chlorophyll so that stain shows up)

3. Drop Iodine Solution on leaf

(If turns from brown to black, starch is present).

Photosynthesis, Respiration and Balance Between the Two

Respiration

Respiration is the release of energy from glucose in living cells to enable life processes.

Word Equation =

Respiration occurs in every living cell

Sometimes called Aerobic Respiration which means it uses Oxygen from the air.

Proving that Carbon Dioxide is produced during Respiration

Testing carbon dioxide is present involves bubbling the gas through lime water. If it turns

milky white then carbon dioxide is present.

Proving that Water is produced during Respiration

Exhale onto cold surface to collect condensation. Add anhydrous copper sulphate to

liquid collected. If it turns from white blue water is present. Or use anhydrous cobalt chloride paper, if water is present turns from blue pink.

Balance Between the Two

Plants photosynthesise and respire.

Plants respire 24 hours a day (steadily because they do not move about)

Plants photosynthesise during the day or when light is present

Think of these different scenarios with an indicator (hydrogencarbonate) which shows the levels of CO2 .

What changes will occur?

Photosynthesis removes Carbon Dioxide from the surroundings.

Respiration adds Carbon Dioxide to the surroundings.

Respiration is NOT breathing. Think of it as burning glucose to release its energy.

(Remember burning needs oxygen to happen)

Glucose + Oxygen Carbon Dioxide + Water + Energy

Possible Revision Method—The Model Room

Draw a picture of a room below. Decide on a logical order for each memory trigger.

Then associate it with a fact to be learned on the process of photosynthesis.

Can be adapted, and you can walk around a room, to help you with your associations

(good for kinaesthetic learners)

For example:

Plant in photo—name of

process photosynthesis

Sunlight in picture—hits

plants and starts reaction

CO2 Clock—Carbon dioxide and water needed for photosynthesis.

Green in picture—

represents the chlorophyll.

Sofa—represents the oxygen and

glucose that is produced.

Possible Revision Method—Flow charts

Write down the steps of a process (procedure) as keywords or short phrases the show

the connections by using arrows.

A good technique to learn the method for testing for starch.

STEP 1:____________________

___________________________

___________________________

STEP 2:____________________

___________________________

___________________________

STEP 3:____________________

___________________________

___________________________

STEP 4:____________________

___________________________

___________________________

STEP 5:____________________

___________________________

___________________________

STEP 6:____________________

___________________________

___________________________

Questions

If you have revised the previous sheets effectively you should be able to answer the following

questions without difficulty.

1. Complete the following word equation.

2. Name two necessary conditions for photosynthesis to occur.

3. When testing for starch why do you boil the leaf in water first?

4. What colour change do you witness in Iodine Solution when starch is present?

5. How can you prove that light is necessary for Photosynthesis?

6. Why do you need to destarch a plant before testing to see if photosynthesis has occurred?

7. What substance removes Carbon Dioxide from the surroundings?

8. What fuel does respiration require in order to produce energy?

9. Where does respiration occur?

10. What gas is given off during respiration and how can you prove this?

11. What gas would be detected by a probe if placed near a plant at midnight? Why?

12. Why do levels of photosynthesis fluctuate during a 24 hour period?

13. Why do levels of respiration stay constant in plants during a 24 hour period?

Carbon Dioxide + ______________ _________________ + Oxygen

For extra info or help with revision use the following pages in the KS3 CGP The Study Guide

Photosynthesis pg. 19

Respiration pg. 4

Microscopes and Cells

The Microscope

Used to view things too

small for the naked eye.

Consists of lenses of

different magnification to

make things appear bigger in

the viewfinder.

Eye Piece x10 magnification

Objective Lenses x10, x20

and x40.

Magnification and Estimation

It is often necessary to estimate the size of an organism

from an image produced by a microscope.

You need to know the magnification of the image and

use a ruler to measure the image carefully.

Magnification x 500

Making a temporary slide

Specimens viewed down a microscope are usually placed and possibly stained (to

enable parts of the cell to be seen) on a glass slide to help isolate the specimen.

Revise the process of producing the slide

If an eye piece with magnification x20 is used and an objective lens with a magnification of x40 the total

magnification is x800 (20 x 40).

1. Place specimen on slide.

2. Place a drop of stain over

specimen.

3. Lower a cover slip over stain

and specimen edge first, using a

mounted needle.

Cells

The building blocks of all living organisms. They combine to form tissue which

combines to form organs.

Tissues are lots of cells with the same job.

Organs are tissues cooperating to perform a function.

Organ Systems are organs with cooperate to perform a life function.

Organelles and their functions.

Found in both Animal and Plant

Cell Membrane – Controls what enters and exits the cell

Cytoplasm – Where chemical reactions take place within the cell

Nucleus – Contains DNA which controls the functions taking place in the cell.

Mitochondria – the site of respiration in cells.

Found only in Plants

Cell Wall – Provides structure and support to the cell. Rigidity. Made of Cellulose.

Chloroplast – Contains Chlorophyll which helps photosynthesis take place.

Vacuole – Contains cell sap which helps maintain the shape of the cell.

Specialised Cells

Sperm Cell

Small cell which contains half

the genetic information in

the nucleus in its head. Has

a tail for swimming to make

its way to fertilise the ovum.

Root Hair Cell

Cell within the roots of a

plant with projections which

help increase surface area to

help absorb lots of water.

Red Blood Cell

Carries oxygen around the

body. Has a dimple to in-

crease the surface area for

oxygen to bind to the cell.

Possible Revision Method—Mind Map

Mind maps can be used to represent key information. When designing a mind map you

should look to connect ideas, using keywords and including diagrams to help you

visualise a concept.

CELLS

Questions



1. What do microscopes enable scientists to do?

2. Which part of the microscope is responsible for magnifying the image?

3. Estimate the length of the head of the creature in the picture on the first page.

4. Why do you sometimes need to stain specimens?

5. Why do you think a cover slip is placed over the specimen?

6. What is a cell?

7. What do cells combine to form?

8. Name three organelles not present in an animal cell?

9. What does the chloroplast do?

10. What is the nucleus for?

11. What is the job of the cell membrane?

12. What is the cell wall made from?

13. What is the main specialised feature of a sperm cell?

14. Why do root hair cells have small projections coming out of them?

15. Why does a red blood cell have a dimple?


The Microscope pg. 1

Cells & Cell Organisation pg. 2 & 3

Health, Nutrition and Digestion

Health

Microbes and Disease

Microorganisms come in different

varieties and sizes.

From largest to smallest

Protozoan

Bacteria

Virus

They cause disease in living

organisms e.g. Smallpox or influenza.

Pathogen = Disease causing microorganism

Host = Organism affected by pathogen

Protection form disease: Good levels of hygiene. Washing hands

Prevention of entry of microorganisms into body – Forming of scabs, wearing of plasters

White blood cells kill bacteria and viruses if unwanted in body Vaccination – prevention of infection

Nutrition

Good for Health Bad for health

Regular exercise Excessive eating

Balanced diet Poor diet

Vitamins Lack of exercise

Hydration Drug abuse

Excessive Alcohol intake

Part of diet Foods rich in substance Reason for needing it

Fats Meat, Dairy Source of energy, helps insulate body

Proteins Meat, Poultry, Nuts Cell repair and growth

Simple Carbohydrates Sweets, Chocolate Quick energy release

Complex Carbohydrates Bread, Pasta, Rice Slow energy release

Vitamins Vegetables and Fruit Improved cell function

Fibre Wholemeal bread, Fruit Aid food moving through digestive system.

Food Tests:

Starch: Adding Iodine solution to food. If starch is

present the colour change is from

red/brown blue/black

Sugar: Add Benedicts Reagent. If sugar is present a

Brick Red precipitate is formed in the reagent. Traces

of sugar cause green/yellow/orange colour.

Fats: Add one or two droplets of ethanol. Add this

ethanol to water. If a white suspension forms fats are present.

Digestion

The mechanical and chemical breakdown of large food molecules into smaller molecules which

can be easily absorbed into the blood.

Not to be confused with:

Ingestion – consumption of a substance

Egestion – removal of undigested food or faeces from gut (make sure to know the difference

between egestion and excretion)

Enzymes:

Produced in the various glands including the pancreas. They are mostly secreted into

the duodenum to be mixed with food and to chemically breakdown the food.

Different enzymes are produced for different substances (lock and key model).

e.g. Amylase in saliva is used to breakdown starches.

Can be denatured (stopped from working) if the pH or temperature is too high.

Benedicts Reagent

Possible Revision Method—Mind Map

Mind maps can be used to represent key information. When designing a mind map you

should look to connect ideas, using keywords and including diagrams to help you

visualise a concept.

Create a mind map on the different type of nutrients include food tests

Possible Revision Method—Flow charts

Write down the steps of a process (procedure) as keywords or short phrases the show

the connections by using arrows.

Use a blank piece of paper.

Create a flow chart on the digestive process

Attempt below.

Questions



1. When does alcohol consumption become dangerous?

2. Name one factor that aids a healthy lifestyle.

3. Name three types of microorganism.

4. Which is the smallest in size?

5. Name two forms of defence against infection?

6. What is the difference between pathogen and host?

7. What is the role of fat in our diet?

8. Name a foodstuff that contains high levels of complex carbohydrates?

9. What is the difference between complex and simple carbohydrates?

10. What are proteins used for in our diet?

11. What is the test for starch in foods? Describe colour change.

12. What is the test for sugars in our diet? Describe colour change.

13. What is digestion?

14. Where is the first site of mechanical breakdown of food in the digestion process?

15. What is mixed with food in the duodenum?

16. Name one source of enzymes in the human body.

17. What can denature enzymes and stop them from working effectively?


Nutrition pg. 6 & 7

Digestion pg. 8 & 9

Health and Drugs pg. 17

SCIENCE YEAR 7 REVISION GUIDE—CHEMISTRY SECTION

Element = Substance consisting of one type of atom

Compound = Substance consisting of two or more different elements chemically combined

Mixture = Substance containing two or more elements or compounds that

have not been chemically joined.

Molecule = A groups of atoms chemically joined e.g. water H2O, oxygen O2

The Atom

Particle Theory As particles are heated they gain kinetic energy. As they are cooled they lose kinetic energy.

Elements Elements form the periodic table.

Metal Oxides are BASIC and SOLID

For example magnesium + oxygen magnesium oxide

Non-metal Oxides are ACIDIC and GASES

For example carbon + oxygen carbon dioxide

Elements, Compounds and Mixtures

Consists of three different units. Electrons (negatively charge and

whizzing around the outside), Protons (Positively charged and in the

nucleus.) and Neutrons (no charge and in nucleus).

Atoms combine to form compounds.

Name Symbol

Hydrogen H

Carbon C

Sulphur S

Iron Fe

Copper Cu

Sodium Na

Oxygen O

Nitrogen N

Calcium Ca

Helium He

Magnesium Mg

Potassium K

Non-metals Metals

Compounds

Compounds are formed when two or more elements combine.

Compounds have different properties to the elements that combine to make them.

Naming Compounds

1. –ide = Two elements joined together e.g. Iron + Sulphur Iron Sulphide

2. –ate = More than two elements joined together with oxygen being one of them

e.g. Copper + Sulphur + Oxygen Copper Sulphate

Class practical: Iron + Sulphur Iron Sulphide

Look at the observations made during this reaction.

Chemical Symbols

Chemical symbols are used to represent compounds. The numbers relate to how many atoms there

are in the compound.

Water has two Hydrogen atoms

Conservation of mass – The mass of the reactants equals the mass of the products. For example,

Magnesium gets heavier when heated in air because it chemically combines with oxygen to form

Magnesium oxide (Mg MgO).

Mixtures

Mixtures are two elements or compounds that are together but not chemically joined.

Dissolving is a good way to form a mixture.

Mixtures can be easily separated (See separating substances section when complete)

You need to recognise this reaction. It shows that a new substance is formed.

Before reaction Iron is magnetic. Iron Sulphide is not

and therefore proves a new substance has been formed.

H2O and one Oxygen atom

Possible Revision Method—Summary Cards

Summary Cards contain the most important details of a topic. You should try to create

a summary of the information, including key words, concepts and diagrams.

Su

mm

ary T

op

ic: E

lemen

ts, Com

pou

nds a

nd M

ixtures

Card

No

. __

__

____

__

Questions



1. What three particles combine to form an atom?

2. What is the name given to the negatively charged particle in an atom?

3. Define an element.

4. Define a compound.

5. Define a mixture.

6. Draw diagrams to represent the particles in each of the states of matter below.

7. Where do you find non-metals on the periodic table?

8. Copper + Oxygen ___________________

9. Copper + Sulphur + Oxygen ____________________

10. Iron + Sulphur ___________________

11. How can you tell that a reaction is occurring (or has occurred) between Iron + Sulphur in

the production of Iron Sulphide? Give two reasons

12. How many Carbon atoms are there in a molecule of Glucose?

C6H12O6

Solid Liquid Gas


Atoms and Elements pg. 35

Periodic Table pg. 36

Compounds pg. 37

Naming Compounds pg. 38

Mixtures pg. 39

Making and Testing Gases & Gases in the Air

Hydrogen

Making Hydrogen

METAL + ACID SALT + HYDROGEN

MASH

Testing for Hydrogen

Using a lit splint the hydrogen should ignite with a

squeaky pop.

Oxygen

Making Oxygen

Thermally decompose (heat) potassium permanganate

Testing for Oxygen

Using a glowing splint plunge into oxygen and it should relight.

Carbon Dioxide

Making Carbon Dioxide

METAL CARBONATE + ACID WATER + SALT + CARBON DIOXIDE

MCAWSCD

Testing for Carbon Dioxide

Bubble carbon dioxide through limewater. Limewater turns

milky white.

Collecting Gas over water

If a gas needs to be collected it should be done over water as shown in diagram be-

low. (Learn the diagram!)

Gases in the Air

Air is a mixture of gases

It consists of different quantities of a variety of different gases

To prove the percentage of oxygen you can use the set up shown below. Heat the copper

filings between the syringes to form copper oxide and remove oxygen from the air within the

syringes. The syringe should read 100ml at the beginning and 79ml at the end thus showing ox-

ygen is 21% of air.

HEAT

Gas Percentage of

Air

Nitrogen 78%

Oxygen 21%

Carbon Dioxide 0.03%

Argon and other

trace gases Trace amounts

Possible Revision Method—Review Cards (Flash Cards)

Review Cards pose questions with long answers or facts on the back.

Flash Cards can be used to learn key words or definitions

SC

IEN

CE

: Mak

ing an

d Te

sting G

ases

Questio

n

Answ

er(s)

Questions



1. How is Hydrogen made in a lab?

2. How do you test for Hydrogen?

3. How is Oxygen made in a lab?

4. Do you use a lit splint or glowing splint to test for oxygen?

5. What substance is used to test for carbon dioxide?

6. What change is seen in this substance if carbon dioxide is present?

7. Write the word equation for the production of carbon dioxide.

8. Write the word equation for the production of hydrogen.

9. Draw the diagram for the collection of gas over water.

10. Why does gas rise to the top of the test tube when being collected over water?

11. What is the percentage of Nitrogen in the atmosphere?

12. If 100cm3 of Air is passed over copper filings which are being heated. After several

minutes what will be the volume of air?

13. Why?

Fuels

Fuels react with oxygen to release energy. Most fuels contain hydrocarbons.

These are compounds of hydrogen and carbon only.

Complete Combustion: Complete combustion releases more energy than

incomplete combustion. It requires a plentiful supply

of air so that the elements in the fuel react fully with

oxygen.

The general equation for complete combustion is:

hydrocarbon + oxygen carbon dioxide + water

Incomplete Combustion:

Incomplete combustion occurs when the supply of air or oxygen is poor, resulting in carbon

monoxide being produced rather than carbon dioxide and producing some carbon (soot) which

has not be oxidised.

The general equation for incomplete combustion is:

hydrocarbon + oxygen carbon monoxide + water

or

Hydrocarbon + oxygen carbon + water

The Bunsen Burner

Air hole open

When the air

hole is open, air

is drawn into the

chimney, where

it mixes with the

natural gas. This

ensures complete

combustion.

Air hole closed

When the air hole is closed

the natural gas can only mix

with air at the mouth of the

chimney. Incomplete

combustion occurs as a

result. A yellow flame is

produced, which transfers

less heat energy than the

blue flame.

Questions



1. How can you test that carbon dioxide gas was produced?

2. What is a test to determine that water is present?

Acids, Alkalis and Neutralisation

Acids

Have a low pH

Have a sour taste (tartaric acid used in toxic waste sweets!!)

Contain Hydrogen and are used to make Hydrogen in reactions with metals.

Make Carbon Dioxide in reactions with carbonates.

Can react to produce salts – Hydrochloric Acid Chloride Salts, Nitric acid Nitrate

Salts, Sulphuric Acid Sulphate Salts etc.

Alkalis

Have a high pH

Soapy texture (often used in cleaning fluids)

Alkalis are soluble bases (bases which have dissolved)

All alkalis are bases but not all bases are alkalis.

Bases

Substances which can neutralise an acid.

When dissolved in water to form a solution are called alkalis

Usually metal oxides, hydroxides or carbonates e.g. Magnesium Oxide, Sodium

Hydroxide.

The pH Scale

Used to help identify the strength of an acid or base/alkali.

Universal Indicator is used to help show the pH by checking the colour

it turns against the colour chart.

If an acid is diluted its pH does not change significantly.

Neutralisation

When acids and alkalis are combined to form salts.

The salt contains the metal from the alkali and part of the acid molecule.

eg Sodium Hydroxide + Hydrochloric Acid Sodium Chloride + Water

The salt depends on the type of acid e.g. sulphuric acid forms

sulphate salts.

ACID + ALKALI SALT + WATER

The Reactions of Acids with Alkalis, Bases, Metal Carbonates and Metals

The Rules

Bases are metal oxides or metal hydroxides, e.g. iron oxide and calcium hydroxide.

Alkalis are bases which dissolve in water. They are always metal hydroxides, e.g.

potassium

hydroxide and sodium hydroxide.

Metals all conduct electricity. Lots of them have names ending in ‘-ium’ although

there are a few

non-metals which also end in ‘-ium’. They include metals with common names like

copper, lead and aluminium.

Metal Carbonates are all metals combined with carbonate groups, e.g. copper

carbonate, potassium carbonate and iron carbonate. They are also classified as bases

because they neutralise acids, but they react with acids in a different way to metal

oxides and metal hydroxides.

Acids all contain hydrogen. The three we need to know are hydrochloric acid,

sulphuric acid and nitric acid.

Hydrochloric acid reacts to form chloride salts

Sulphuric acid reacts to form sulphate salts

Nitric acid reacts to form nitrate salts.

The Rules II

Base + Acid Water + Salt (BAWS)

Acid + Alkali Water + Salt (AAWS)

Metal + Acid Salt + Hydrogen (MASH)

Metal Carbonate + Acid Water + Salt + Carbon Dioxide (MCAWSCD)

A salt is a metal sulphate, metal chloride or metal nitrate.

Hydrochloric acid makes chloride salts

Sulphuric acid makes sulphate salts

Nitric acid makes nitrate salts Phosphoric acid makes phosphate salts

Neutralisation Reactions

1. Sulphuric Acid + Copper oxide

2. Nitric Acid + Iron carbonate

3. Hydrochloric acid + sodium hydroxide

4. Sulphuric acid + Zinc

5. Acetic acid + aluminium

6. _____________ + ____________ lead nitrate + carbon dioxide + water

7. ______________ + Magnesium Magnesium chloride + _____________

8. Nitric acid + ____________ Calcium __________ + water

9. Zinc oxide + Nitric acid

10. Magnesium hydroxide + sulphuric acid

11. Copper + hydrochloric acid




SC

IEN

CE

: Neutralisatio

n Salt N

ames

Questio

n

Answ

er(s)

Questions



1. Is an acid’s pH low or high?

2. What chemical element do all acids contain?

3. Name a household acid.

4. What chemical compound do acids always produce in the reactions you have learnt?

5. What acid produces chloride salts?

6. What acid produces sulphate salts?

7. What acid produces nitrate salts?

8. What is an alkali?

9. Is an alkali’s pH high or low?

10. Name a household alkali.

11. Give two examples of bases.

12. What is the pH scale used for?

13. How do you find the pH of a chemical? (include all detail!) [3 marks]

14. Does an acid’s pH change much if water is added to it?

15. What determines which salt is produced in a neutralisation reaction?


Acids and Alkalis pg. 52

Neutralisation Reactions pg. 53

Reaction of Metals with Acids pg. 55

Reaction of Oxides with Acids pg. 56

SCIENCE YEAR 7 REVISION GUIDE—PHYSICS SECTION

Energy

Types of Energy

Energy can be found in several different forms or types. You need to remember 8!

ENERGY Chemical

Strain

(Elastic)

Kinetic

Light

Gravitational

Potential

Heat Electrical

Sound

Law of Conservation of Energy

Microphone: Sound Electrical

Fire: Chemical (wood) Heat + Light

Skydiver: Gravitational Potential (In Plane) Kinetic (Falling)

Renewable and Non-Renewable Energy Sources

Non-Renewable

An energy resource that will not be replenished in one’s lifetime.

Fossil Fuels are prime examples of non-renewable energy sources.

Oil (Chemical Heat + Light)

Coal (Chemical Heat + Light)

Gas (Chemical Heat + Light)

All fossil fuels originally derived their energy from the sun when the organisms that

formed them were alive.

Fossil Fuels will run out. It takes millions of years for them to be made.

They are all energy in the form of chemical energy.

Renewable

An energy resource that will be replenished in one’s lifetime.

Sometimes more expensive to initiate but more kind on the environment

Examples include: Solar (light electrical or heat), Wind (kinetic electrical), Tid-

al (kinetic Electrical), Hydroelectric (Kinetic Electrical)

Thermal (Heat) Energy

Thermal energy is one of the most common forms of energy. It can transfer from

one place to another in a variety of different ways.

Conduction transfers heat through solids.

Convection transfers heat through convection currents in liquids and gases.

Radiation can pass through a vacuum.

Convection Current

Possible Revision Method—Create a Mnemonic

An mnemonic is a made up rhyme to help you memorise lists of information.

Mnemonic—Energy Types




Question

SCIENCE: Heat Transfers

Answer(s)

Questions



1. Name eight different types of energy.

2. Which type of energy is gained when you climb a ladder?

3. Which type of energy is stored in our food?

4. What is the law of conservation of energy?

5. What energy transfer occurs in a guitar amplifier?

6. What energy transfer occurs when BBQ fuel burns?

7. What energy transfers occur in a Hydroelectric Power plant? (more than those stated)

8. Name three types of fossil fuel.

9. Name three types of renewable energy source.

10. What is a drawback of renewable energy?

11. What is a positive of renewable energy?

12. Why are fossil fuels not a good source of energy for the future?

13. Name the three methods by which thermal energy can be transferred.

14. What happens to heat energy during convection?

15. How do radiators heat a room effectively?

16. Is radiator a good name for a radiator?


Energy Transfers pg. 66 & 67

Heat Transfer pg. 68

Conservation of Energy pg. 69

Energy Resources pg. 70

Generating Electricity pg. 71

Light & Sound

Light

Part of the electromagnetic spectrum (Visible spectrum)

Travels in strait lines

Reflection

Angle of incidence (i) = Angle of reflection (r)

Refraction

Refraction is when light changes direction due to a change of speed as it enters from

one medium to another.

When light slows down it moves towards the normal.

When light speeds up it moves away from the normal.

The normal is drawn perpendicular (at right angles) to the surface of the new medium.

Dispersion

White light consists of a combination of the different colours of the rainbow.

White light must be refracted twice in a prism to disperse into its different colours

(the spectrum).

Diagrams: You should be able to draw basic diagrams of

Reflection, Refraction and Dispersion.

Knowing how to draw them should help you remember how the light is affected and how it moves.

The angle of reflection and incidence are

measured between the ray and the normal,

not the ray and the reflective surface.

Sound

Made by vibrating matter

Travels much slower than light (speed of sound in air is 330m/s)

Frequency and Amplitude are two different measurements taken from sound

Frequency

The number of vibrations in one second.

How high or low (pitch) the sound is—high

frequency equates a high pitch; a low frequency

equates a low pitch.

Stringed instrument:

To change frequency—shorten string, tighten string,

make string thinner

Drum:

To change frequency—tighten skin, make skin thinner

Amplitude

Changes the volume of the sound

Stringed Instrument:

To change amplitude—pluck strings harder.

Drum:

To change amplitude— hit the skin harder.

Sound travels in Waves

Two types of wave: Transverse and Longitudinal

The shorter the wavelength (see diagram below) the higher the frequency.

These are graphs of sound waves—sound waves themselves are longitudinal.

Sound travelling through different mediums

Light travels faster through solids than liquids and gases. This is because the particles are closer

together and thus pass vibration on more efficiently.

Echoes: occur when sound reflects of a

surface and travels back to where it was

made.

Used to measure distances. For example,

sonar or echolocation

Possible Revision Method—Audio

For auditory learners, try reading the information aloud, record yourself reciting key facts,

use video clips, put key facts into a well known tune or talk about your learning to

others.

Possible Revision Method—Summary Cards

Summary Cards contain the most important details of a topic. You should try to create

a summary of the information, including key words, concepts and diagrams.

Su

mm

ary T

op

ic: Ligh

t—Refra

ction, R

eflection a

nd D

ispersion

Card

No

. ________

Questions



1. What is unusual about how light travels?

2. Does light travel faster or slower than sound in air?

3. When light rays hit a mirror what process do they undergo?

4. What is the relationship between the angle of incidence and the angle of reflection?

5. Where do you draw the normal on a light ray diagram?

6. What happens when light travels from glass to air?

7. If light slows down when travelling from one medium to another does it bend towards or

away from the normal?

8. What happens when light rays are shone through a prism and refracted twice?

9. Draw diagrams of Reflection, Refraction and Dispersion.

10. What is it that makes sound?

11. What is frequency?

12. What is amplitude?

13. What is the relationship between wavelength and frequency?

14. How do you change the frequency of sounds coming from a guitar?

15. How do you change the amplitude of sounds coming from a drum?

16. What is an echo and how can it be useful?

17. Does sound travel faster in water or iron? Why?


Light Waves pg. 87

Reflection and Refraction pg. 88

How We See pg. 89

Colour pg. 90

Sound pg. 91

Hearing pg. 92

Density, Pressure and Speed Calculations

Density

Mass per unit of volume

Measured in g/cm3 or kg/m3

Density (g/cm3) = Mass (g) / Volume (cm3)

Mass (g) = Density (g/cm3) x Volume (cm3)

Volume (cm3) = Mass (g) / Density (g/cm3)

Pressure

Force per unit of area

Measured in N/m2 or N/cm2

Sometimes measured in Pascals. 1 pascal = 1N/m2

Pressure (N/m2) = Force (N) / Area (cm2)

Force (N) = Pressure (N/cm2) x Area (cm2)

Area (cm2) = Force (N) / Pressure (N/cm2)

Speed

Distance per unit of time

Measured in m/s or km/h

Speed (m/s) = Distance (m) / Time (s)

Distance (m) = Speed (m/s) x Time (s)

Time (s) = Distance (m) / Speed (m/s)

D = M/V

M = D x V

V = M/D

P = F/A

F = P x A

A = F/P

S = D/T

D = S x T

T = D/S

Conversions

Please be careful that you convert units appropriately and effectively. Remember the following:

1 metre = 100 cm

1 kilometre = 1000 m

1 m2 = 10000 cm2

1 m3 = 1000000 cm3

1 litre = 1000 ml

Questions



1. What is a more unusual unit used for pressure?

2. Without looking on the previous page. Write the full word equations (with units) for all

3 calculations relating to Density.


3 calculations relating to Pressure.


3 calculations relating to Speed.

5. How many metres in 1.53 km?

6. How many litres is 897ml?

7. How many metres is 1240cm?

8. What is the volume of a stone that has a mass of 120g and a density of 4g/cm3?

9. Mo Farah took 13mins 40s to complete the 5000m race at the London 2012 Olympics.

How fast was he

running on average?

10. How much pressure does the stiletto with an area of 1.4cm2 exert on the floor when a

woman weighing 500N stands on one leg?

11. What is the density of grandma’s fruit cake? It is a cuboid shape with a height of 10cm,

width of 15cm and length of 30cm and when placed on the scales measures in at 1kg.

12. Yohan Blake was clocked running 100m in training at an average of 40km/h. Would he beat

Usain Bolt’s 100m World record of 9.58s?


Speed pg. 77

Pressure pg. 84

Dulwich Prep London

42 Alleyn Park | London SE21 7AA | Telephone 020 8766 5500 | Fax 020 8766 7586 | www.dulwichpreplondon.org

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