UPDATED
© Keith and Ann Johnson 1978, 1980, 1986, 1991, 2001, 2006, 2011 The right of Keith Johnson to be identified as author of this work has been asserted by him in accordance with the Copyright, Designs and Patents Act 1988. All rights reserved. No part of this publication may be reproduced or transmitted in any form or by any means, electronic or mechanical, including photocopy, recording or any information storage and retrieval system, without permission in writing from the publisher or under licence from the Copyright Licensing Agency Limited, of Saffron House, 6–10 Kirby Street, London EC1N 8TS. Any person who commits any unauthorised act in relation to this publication may be liable to criminal prosecution and civil claims for damages. This edition published in 2011 by: Nelson Thornes Ltd, Delta Place, 27 Bath Road, CHELTENHAM, GL53 7TH, United Kingdom ISBN 978 1 4085 0922 7
11 12 13 14 15 / 10 9 8 7 6 5 4 3 2 1
A catalogue record for this book is available from the British Library Page make-up by Tech-Set with additional typesetting by Fakenham Photosetting Printed and bound in China by 1010 Printing International Ltd
Website: The website at www.physicsforyou.co.uk gives you details of exactly which pages in this book you need to study for your particular GCSE examination course. Make sure you visit this website and print out the correct sections. They will show you: which topics you need to learn for your particular examination, and which page numbers to read in this book.
• •
‘What is the use of a book,’ thought Alice, ‘without pictures or conversations ?’ Lewis Carroll, Alice in Wonderland Everything should be made as simple as possible, but not simpler. Albert Einstein There is no higher or lower knowledge, but one only, flowing out of experimentation. Leonardo da Vinci I do not know what I may appear to the world, but to myself I seem to have been only a boy playing on the seashore, and diverting myself in now and then finding a smoother pebble or a prettier shell than ordinary, while the great ocean of truth lay all undiscovered before me. Sir Isaac Newton
Introduction Physics For You is designed to introduce you to the basic ideas of Physics, and show you how these ideas can help to explain the world in which we live.
At the back of the book there is advice for you on practical work, key skills, ideas and evidence in science, careers, revision and examination techniques, as well as help with mathematics.
This book is based on successful earlier editions of the same name, but new pages and extra questions have been added to cover the latest requirements of the new GCSE Examinations.
Questions at the end of a chapter range from simple fill-in-a-missing-word sentences (useful for writing notes in your notebook) to more difficult questions that will need some more thought. In calculations, simple numbers have been used to keep the arithmetic as straightforward as possible.
Physics For You has been designed to be interesting and to help you to pass your exams, whether you are using it for a Physics course or as part of a Core Science or Additional Science course. The book is carefully laid out so that each new idea is introduced and developed on a single page or on two facing pages. Words have been kept to a minimum and as straightforward as possible. Pages with a red band in the top corner are the more difficult pages and may be left out at first. Throughout the book there are many simple experiments for you to do. A safety sign: ! means your teacher should give you further advice (for example, to wear safety glasses). Each important fact or new formula is printed in heavy type or is in a box. There is a summary of important facts at the end of each chapter.
At the end of each main topic you will find a section of further questions taken from actual GCSE examination papers. Throughout the book, cartoons and rhymes are used to explain ideas and ask questions for you to answer. In many of the cartoons, Professor Messer makes a mistake because he does not understand Physics very well. Professor Messer does not think very clearly, but I expect you will be able to see his mistakes and explain where he has gone wrong. Here I would like to thank my wife, Ann, for her constant encouragement and her help with the many diagrams and cartoons. I hope you will find Physics interesting as well as useful. Above all, I hope you will enjoy Physics For You. Keith Johnson
Professor Messer gets in messes, Things go wrong when he makes guesses. As you will see, he’s not too bright, It’s up to you to put him right. 3
Contents Basic ideas
The small . . .
1 2 3 4
How Science works Units 8 Energy 10 Molecules 16
6
Heat (thermal energy) 5 6 7 8 9
Expansion 21 Thermometers 26 The Gas Laws 29 Measuring Heat 35 Conduction, Convection, Radiation 40 Physics at work: Keeping warm 43 10 Changing State 53 Further questions on heat 60 Seven atoms in a uranyl microcrystal, photographed with an electron microscope and false colour added. They are magnified 100 million times.
Mechanics 11 12 13 14
. . . and the large. 15 16 17 18 19
Pushes and Pulls 64 Density 74 Pressure 77 More about Forces 82 Physics at work: Friction 83 Physics at work: Parachutes 89 Turning Forces 90 Work, Energy and Power 97 Physics at work: Supplying electricity 105 Machines 116 Velocity and Acceleration 122 Physics at work: Sport 134 Momentum 136 Further questions on mechanics 140
Earth Physics and Astronomy
The Andromeda galaxy. It contains about 100 000 million stars, and the distance across it is over 100 000 light-years (10 21 metres).
4
20 The Earth and beyond 146 Physics at work: Satellites 154 Physics at work: Space travel 160 Further questions on astronomy 163
Waves: Light and Sound
Nuclear Physics
21 22 23 24 25
39 Radioactivity 338 Physics at work: Radioactive dating 352 Further questions on radioactivity 353 Physics at work: Medical physics 356
Waves 166 Light 171 Reflection 176 Curved Mirrors 181 Refraction 184 Physics at work: Fibre optics 192 Physics at work: Lasers 193 26 Lenses 194 27 Optical instruments 198 28 Colour 206 Physics at work: Electromagnetic waves 212 Physics at work: Telescopes in space 215 Physics at work: Mobile phones 216 Physics at work: Analogue and digital 218 29 Sound 224 Physics at work: Ultrasonic echoes Further questions on waves 236
228
Extra sections How Science works 358 Doing Your Coursework 366 How scientists work 370 Ideas changing over time 371 Famous Names 376 History of Inventions 378 Key Skills
380
Electricity and Magnetism 30 Static Electricity 241 Physics at work: Static electricity 246 31 Circuits 248 32 Heating Effect of a current 264 Physics at work: Circuit-breakers 272 33 Chemical Effect of a current 273 Further questions on Electricity (1) 276 34 Magnetism 280 Physics at work: Magnets 284 35 Magnetic Effect of a current 286 Physics at work: Using electromagnets 288 36 Electromagnetic Induction 296 Physics at work: In your home 306 37 Electron beams 308 Physics at work: In the office 314 38 Electronics 316 Physics at work: Radio 331 Further questions on Electricity (2) 332
Revision Techniques 382 Revision Programme 384 Revision Checklist 385 Examination Technique Careers using Physics Check your Maths Answers Index
386 388
390
392
396
Revision details at www.physics for you.co.uk 5
chapter 1
How Science works The main purpose of this book is to help you gain scientific knowledge and understanding. But you also need to know ‘How Science works’, and how scientists work. You will learn a lot of this by planning and then doing your own experiments and investigations, to collect data (see the opposite page). How scientists work The purpose of Science is to find out how the Universe works. We are trying to explain the world in which we live. We do experiments and investigations to observe and collect evidence, rather like detectives investigating a crime. From the evidence scientists try to form a theory or ‘thought-model’, to explain the evidence. (For example, the kinetic theory of molecules on page 16.) A good theory or model is one which can be used to make a prediction, which we can test by experiment. If the experiment contradicts it, then the theory is modified or changed to a new theory that fits the facts ...until new evidence disproves this theory, and so on. In this way, human understanding of our world has developed step by step. This is how Science works.
‘Practical skills are important’
As Albert Einstein said: “No amount of experimentation can ever prove me right; but a single experiment may prove me wrong.”
The history of Science shows how scientific ideas have changed step by step (see pages 371–379). In the modern world, scientists usually work in teams and share their ideas with other teams, by publishing them in books or on the internet (see page 370 for more details). It is vital that their evidence is reliable and valid. It is then for society as a whole to make decisions based on that evidence. For example, what to do about global warming (see page 107). Of course there are many questions that Science cannot answer yet (eg. how to cure all cancers). And there are questions that Science can never attempt to answer (eg. religious questions).
Science can explain how we see a flower, ...but it cannot explain why it looks beautiful.
The opposite page gives a summary of the key words used in Physics investigations. There are more details about How Science works on pages 358–365. 6
Read through the box below, and discuss any difficult words in your group or with your teacher. See also the Glossary below. Make sure that you understand all of the words. Science is a powerful tool for answering certain questions. To do this we need to plan an investigation to collect data. We can do this by observing and measuring. Usually we are trying to find a link between 2 variables. When planning an investigation we always try to make it a fair test. We need to ensure that the data we collect are reliable and valid. As well as the primary data that we collect, we can also use secondary data. For some investigations we can use ICT, either to take measurements (using a sensor) or to model the situation. When we have collected data, we need to present it clearly, in order to see any patterns in the data. We can use tables, bar-charts and line-graphs to display the data. On a line-graph we can draw a line of best fit. This lets us see any anomalous data that do not fit the pattern. The line of best fit may allow us to draw a conclusion. We should always evaluate our work. This means: – evaluating the investigation to see if it could be improved, – evaluating our data to see if they are reliable and valid.
The main steps in an investigation Plan your investigation
Observe and measure the data
Present your data in tables, charts or line-graphs Analyse the data, and try to draw a conclusion
Evaluate the data and the investigation
Glossary Data : a series of measurements, used as evidence. Variables These are things that you can vary or change during your investigation. There are 3 main types: G independent (or input) variable. This is the thing that you decide to change. G dependent (or outcome) variable. This is the variable that changes as a result. It is the variable that you measure. G control variables. These are all the variables that must not change, so that it is a fair test. Reliable evidence is data that we can trust. If someone else did the same experiment would they find the same evidence ? Your evidence will be more reliable if you repeat the readings. Valid evidence is data that measures what you intended, and is directly relevant to your investigation. Secondary evidence is data collected by someone else. You may find it in a book or on the internet, but you should always check to see if it is reliable and valid.
For example: Variables When you stretch an elastic band, - the independent variable is the force that you apply, - the dependent variable is the length of the elastic (which you can measure). For example: Reliable Measuring the time of a pendulum more than once, and taking an average, gives you more reliable data. For example: Valid Measuring the volume of food is not valid evidence of the amount of energy in it. For example: Secondary data Data on road safety published by a car manufacturer ...but it may be biassed.
7
chapter 2
Length Length is measured in a unit called the metre (often shortened to m). A door knob is usually about 1 metre from the ground; doorways are about 2 m high. We often use centimetres (100 cm = 1 metre) or millimetres (1000 mm = 1 metre). Experiment 2.1 a) Look at a metre rule. Which marks are centimetres and which are millimetres ? b) It is useful to know the length of your handspan. Mine is 22 cm (0.22 m); what is yours ? c) Use the metre rule to measure – the length of your foot – your height. Write down your answers in mm and also in m. To measure short lengths very accurately we can use vernier calipers or a micrometer. When measuring in Physics we try to do it as accurately as we can. Professor Messer is trying to measure the length of a block of wood with a metre rule but he has made at least six mistakes. How many mistakes can you find ? Experiment 2.2 Measure the length of a block of wood taking care not to make any of the Professor’s mistakes.
8
Mass If you buy a bag of sugar in a shop, you will find the mass of sugar marked on the bag. It is written in grams (g) or in kilograms (kg). ‘Kilo’ always means a thousand, so 1 kilogram = 1000 grams. The mass of this book is about 1 kilogram. People often get confused between mass and weight, but they are not the same (see pages 65 and 68). ! Experiment 2.3 Lift some masses labelled 1 kg, 2 kg, 5 kg and 1 g.
Time In Physics, time is always measured in seconds (sometimes shortened to s). You can count seconds very roughly, without a watch, by saying at a steady rate: ONE (thousand) TWO (thousand) THREE (thousand) FOUR . . . ! Experiment 2.4 Use a stopclock or stopwatch to measure the time for a complete swing of a pendulum (see page 99) or the beating of your heart. What is the time for 100 of your heartbeats ? What is the time for one heartbeat ? By how much does it change if you run upstairs ?
All the other units you will meet in this book are based on the metre, the kilogram and the second. They are called SI units. Very large and small numbers For very large or very small numbers, we sometimes use a shorthand way of writing them, by counting the number of zeros (see also page 391). For example: a) 1 million = 1 000 000 (6 zeros) = 106 b) 2 million = 2 000 000 = 2 106 c) 0.000 001 =
1 1 000 000
(1 millionth) = 10
6
In this shorthand way, write down: one thousand, one thousandth, 10 million, one hundredth, 3 million, 30 thousand.
In Maths and in Physics, a ‘k’ Means a thousand of whatever you say For grams and for metres And even, for teachers, The size of their annual pay.
‘kilo’ is not the only prefix: Mega (M) = 1 million
= 1 000 000
kilo (k)
=
= 1 thousand
1 000
1 = 100 1 milli (m) = 1 thousandth = 1000 1 micro (Ȗ) = 1 millionth = 1 000 000 centi (c) = 1 hundredth
1 nano (n) = 1 thousand-millionth = 1 000 000 000
Approximate length of time in seconds 1018 1017 1015 1013 1010 109 107 105 100 102 107 108 1011 1022
Events
Expected lifetime of the Sun Age of the Earth Time since the dinosaurs lived Time since the earliest human Time since Isaac Newton lived Average human life span A school term One day One second Time for sound to cross a room Time for an electron to travel down a TV tube Time for light to cross a room Time for light to pass through spectacles Time for some events inside atoms
9
chapter 3
I wish I could find some use for all that energy !
Energy can exist in different forms, as you can see in the cartoon. People get their energy from the chemical energy in their food. Cars run on the chemical energy in petrol. A firework in the cartoon has chemical energy which it transforms to thermal energy (heat) and light and sound energy when it explodes. Some forms of energy are called potential energy. One kind of potential energy is the elastic energy (also called strain energy) stored in the stretched elastic of a catapult. The bucket over the door also has some stored potential energy, called gravitational potential energy. When the bucket falls down, this gravitational energy is transferred to movement energy. The moving pellets from the catapult and the moving people all have movement energy, called kinetic energy. The television set is taking in electrical energy and transferring it to thermal energy and light and sound energy. Another form of energy is nuclear energy, which is used in nuclear power stations. These forms of energy are shown in the diagram on the opposite page (see also page 98). 10
The connecting lines on the diagram show the different ways that energy can be changed from one form to another. See if you can decide what the energy changes are in the following objects. For example: A firework changes chemical energy to thermal energy, light and sound energy. Copy and complete these sentences. 1. 2. 3. 4. 5. 6. 7. 8. 9. 10.
A TV set changes . . . . . . . . . . . . . . . . . . A match changes . . . . . . . . . . . . . . . . . . A light-bulb changes . . . . . . . . . . . . . . . . A catapult changes . . . . . . . . . . . . . . . . . A falling bucket changes . . . . . . . . . . . . An electric fire changes . . . . . . . . . . . . . A human body changes . . . . . . . . . . . . . A microphone changes . . . . . . . . . . . . . An atomic bomb changes . . . . . . . . . . . A car engine changes . . . . . . . . . . . . . . .
energy energy energy energy energy energy energy energy energy energy
to to to to to to to to to to
......... ......... ......... ......... ......... ......... ......... ......... ......... .........
energy. energy. energy. energy. energy. energy. energy. energy. energy. energy.
You can learn more about energy changes and transfers in chapter 16. 11
Energy changes In the diagram on the previous page (page 11), one energy change has been labelled ‘electric fire’. Copy out the diagram into your book and then add the correct label to every arrow. Use words from the following list: coal fire, electric fire, steam engine, atom bomb (on four arrows), car engine, battery, loudspeaker, dynamo, very hot object, friction, bow and arrow, falling parachutist, cricket ball rising in the air, vibrations, microphone, thermocouple, solar cell, solar panel, plants, glow-worm, fluorescent lamp, girl landing on a trampoline, hanging a weight on a spring, an arm muscle tightening, soundabsorbing material, electroplating. Taking in chemical energy Saving money Energy costs money and we use large amounts of energy/money each day. There are several ways of saving energy/money in your home (and making your home more comfortable at the same time). The table shows the time taken before they have paid for themselves and start to show a ‘profit’. How well is your home insulated ? How well is your school insulated ? Write a list of recommendations. Energy is measured in units called joules. The joule is a small unit. To lift this book through a height of 10 cm needs about 1 joule. When you walk upstairs you use over 1000 joules.
Method
Payback times*
Lagging the hotwater cylinder
Less than a month
Draught excluders
A few weeks
Lagging the loft (see page 43).
About 3 years
Wall cavity insulation
4 –7 years
Double glazing in windows
About 10 years *all these times are shorter if you get a government grant
The diagram below shows the energy (in joules) involved in different events. (Remember: 105 = number with 5 zeros = 100 000 1 and 105 = 100 000 )
energy from
kinetic energy of a bullet
uranium atom kinetic energy of an alpha-particle
10 –13
10 –11
energy needed to lift a hair through 1 mm
10 –9
10 –7
moonlight on energy to lift your face for this book from 1 second
10 –5
10 –3
10 –1
energy from a completely burnt match
1 1J
12
10
10 3 1 kJ
1k for 1 hour (1 kW h)
10 5
day’s work for a woodcutter
10 7
The energy crisis We are only just beginning to realise fully that our planet Earth is a spaceship with limited food and fuel (and we are taking on more passengers each year as the population increases). Our supplies of energy cannot last for ever. Oil and natural gas will be the first to disappear. If the whole world used oil at the rate it is used in America and Europe, our oil supplies would end in about 4 years! They are non-renewable. As it is, the world’s oil supplies might last for about 40 years. How old will you be then ? In what ways will your life be different without oil (and therefore without petrol and plastics) ?
Power stations are wasteful (see p. 104). The overall efficiency (from power station to your home) is about 25 %. Three-quarters of the energy is entirely wasted! The wasted energy could be used to heat nearby homes.
Natural gas will last a bit longer – perhaps 60 years. Coal will last longer – perhaps 300 years with careful mining. Nuclear energy might help for a while – but it causes problems due to the very dangerous radioactive waste that is produced (page 350). Also, each power station lasts only about 30 years and is difficult to dismantle because of the radioactivity. We waste huge amounts of energy. It takes over 5 million joules of energy to make one fizzy-drink-can and we throw away 700 million of them each year! Making paper and steel uses particularly large amounts of energy, but very little is recycled. We must find new ways of obtaining energy. The Sun’s energy is free but it is not easy to capture it. Governments are looking for new sources of energy (see next page). They will probably not give enough energy for the future. Our main hope is that the H-bomb fusion process (page 156) will eventually be controlled.
nuclear 9%
renewable 2%
COAL 17%
OIL 32%
NATURAL GAS 40%
Energy sources of Britain at present. What will happen when the fossil fuels (oil, gas, coal) run out ?
13
Renewable sources of energy Some sources of energy are renewable. They are not used up like coal or oil. Physicists and engineers are working hard to develop better machines to use these sources of energy. Solar energy
Source of energy
Original source
Solar Biomass Wind Waves Hydro-electric Tides Geothermal
Sun Sun Sun Sun Sun Moon Earth
The Earth receives an enormous amount of energy directly from the Sun each day, but we use very little of it. Some homes have solar panels on the roof (see page 50). In hot countries solar ovens can be used for cooking (see page 48) and for producing electricity in solar thermal towers. Space ships and satellites use solar cells to convert sunlight into electricity. You may have seen calculators powered by solar cells. Covering part of the Sahara Desert with solar cells would produce energy but would be very expensive. To equal the power of one modern power station you would need 40 square kilometres of solar cells. Biomass Some of the sunlight shining on the Earth is trapped by plants, as they grow. We use this biomass when we eat plants or when we burn wood. In Brazil they grow sugar cane and then use the sugar to make alcohol (‘bio-ethanol’). The alcohol is then used in cars, instead of petrol. Rotting plants can produce a gas called methane which is the same as the ‘natural gas’ we use for cooking. If the plants rot in a closed tank, called a digester, the gas can be piped away and used as fuel for cooking. This is often used in India. Wind energy This energy also comes from the Sun, because winds are caused by the Sun heating different parts of the Earth unequally. Modern ‘wind-generators’ are very efficient but it takes about 2000 very large wind turbines to provide as much electricity as one modern power station (and only if the wind is blowing). 14
gas
methane gas digester manure and rotting plants
Wave energy
float rocks up and down
Waves are caused by the winds blowing across the sea. They contain a lot of free energy. One method of getting this energy is to use large floats which move up and down with the waves. The movement energy can be converted to electricity. However, we would need about 20 kilometres of floats to produce as much energy as one power station.
ocean waves
pivot
Hydro-electric energy upper lake
Dams can be used to store rain-water, and then the falling water can be used to make electricity (see experiment 16.5 on page 101). This is a very useful and clean source of energy for mountainous countries like Norway and China.
400m
The same idea can be used to store energy from power stations that cannot easily shut down. At night, when demand is low, spare electricity can be used to pump water up to a high lake. During the day, the water can be allowed to fall back down, to produce electricity when it is needed.
large power station inside the mountain
lower lake
A pumped storage scheme in Scotland
Tidal energy As the Moon goes round the Earth it pulls on the seas so that the height of the tide varies. If a dam is built across an estuary, it can have gates which trap the water at high tide. Then at low tide, the water can be allowed to fall back through the dam and make electricity (see experiment 16.5). Geothermal energy The inside of the Earth is hot (due to radioactivity, see chapter 39). In some parts of the world (like New Zealand) hot water comes to the surface naturally. In other countries cold water is pumped down very deep holes and steam comes back to the surface.
A tidal power station in France
Summary Energy exists in several different forms: chemical, electric, magnetic, kinetic, potential (elastic and gravitational), sound, nuclear, electromagnetic radiation (including light) and thermal energy (internal energy or heat).
Energy can be changed from one form to another. Some sources of energy are non-renewable and will be used up: coal, oil, gas, nuclear. Other sources are renewable: solar, biomass, wind, wave, hydro-electric, tidal and geothermal. See also chapter 16, pages 103 –106.
15
Index A absolute temperature 27, 31 absolute zero 27, 31, 34 a.c. 268, 298–9, 317 a.c. generator 298–300 acceleration 122–5, 127, 130–1 acceleration due to gravity 128–9, 131 accuracy 362 acoustics 234 air bag 138 air resistance 87, 89 alpha-particle 340–2, 345, 350 alpha-particle scattering 342 alternating current 268, 298–9, 317 AM (amplitude modulation) 331 ammeter 250 ampere 250, 260 ampère-hour 115 amplifier 322, 325 amplitude 167, 231 analogue 218–9, 306 AND gate 326–9 anode 273–4, 308 asteroids 152 atmospheric pressure 57, 80 atomic mass 343 atomic structure 342 atoms 342–3, 372
B background radiation 340, 350 balance 75 spring 66–7 balloon, hot-air 45 barometer, mercury 80 battery 115, 252, 260 Becquerel, Henri 338, 350, 372 bell, electric 288 beta-particle 340–1, 345 Big-Bang theory 158, 373 bi-metallic strip 23, 25, 272 biomass 14 biometrics 356 black hole 157, 372 boiling 57 and impurities 57 and pressure 57
396
Boyle’s Law 29, 33, 34 braking 79, 83 bridges 22, 73 Brownian movement 18
C calorific value 35 camera, lens 195–6, 198–9 pinhole 174 capacitor 245, 317, 325 car, brakes 79, 83 cooling system 44 driving mirror 182 engine 114–15, 116 headlamp 183 ignition system 304 safety 69, 83, 138 starter motor 289, 292 carbon capture 107 careers 388–9 cathode 273–4, 308, 316 cathode-ray oscilloscope 310–11 cathode rays 309 CD-ROM 218, 306, 314 cell, dry 252, 260 Celsius (centigrade) 26, 27 centre of mass (gravity) 92–5, 134 centripetal force 70–1, 134, 148, 153 chain reaction 348 change of state 53–7 charges, law of force 241 Charles’ Law 30–1, 33, 34 chemical effect of a current 273–5 circuit-breaker 269, 272, 295 circuits, parallel 251, 257, 261 ring main 268–70 series 250, 256, 261 circular motion 70–1, 134, 148, 153 clinical thermometer 27 cloud chamber 338 collisions 137–8 colour-blindness 203, 221 colours, primary 221, 307, 311 secondary 221 comets 152 communications 155, 192, 211, 218–19, 314 commutator 292
compact disc (CD, DVD) 218, 306, 314 computer 314 concave mirror 48, 181–2 conduction, of electricity 243, 249 of heat 40–3 conductors 41, 243, 249 conservation of energy 98, 102, 371 continental drift 373 convection 38, 40, 44–5, 51, 264 convex mirror 181–3 copper, refining of 275 coulomb 245, 260–1 critical angle 187 CRO (oscilloscope) 232, 310–11, 317 crumple zones 69, 138 current : voltage graphs 259, 316 curved mirrors 181–3
D dating, radioactive 347, 352 deceleration 122 decibel 230, 234 defects, of hearing 230, 234 of vision 202–3 demagnetisation 281 density 74–6, 78, 147 depth of field or focus 199 diffraction 155, 169, 211, 226, 228 diffusion 19 digital 218–19, 306, 314, 326 diode 308, 316–17, 321, 331 dispersion 206–7 displacement 126 distance–time graph 126 Doppler effect 158 dosemeter 214, 350 double-glazing 43 dynamo, a.c. 298–300 bicycle 298 d.c. 300
E
F
H
ear 230 Earth 48, 71, 146–55, 282 earthing 268–70 earthquakes 146–7 electrocardiography (ECG) 356 echoes 226, 228–9 eclipse 173 eddy currents 302 efficiency 102–3, 116 of machines 102–3, 116, 118–19, 302 Einstein, Albert 348, 372, 374, 376 elastic (strain) energy 10, 98, 108 elastic limit 66 electric bell 288 electric energy 10, 104–6, 261, 266–7 electric field 244 electric fire 38, 264 electric force 17, 241 electric lamp 103, 212, 259, 265 electric motor 290–3 electric power 111, 266 electricity, generating 104–6, 296–303 electricity meter 267–8 electrolysis 273–5 electromagnet 281, 287–9 electromagnetic induction 296–303 electromagnetic waves 207–15 electron 242, 249, 260–1, 308–12 electronics 316–29 electroplating 274–5 electroscope, gold-leaf 243, 338 electrostatic induction 242 electrostatic precipitator 246 e.m.f. 252 endoscope 192 energy, and work 97, 99, 108 chemical 10, 35, 98 electrical 10, 98, 104–6, 261, 266–7 heat (thermal) 10, 35–8, 98, 101 kinetic 10, 98–9, 109, 137, 224 light 10, 98, 101 nuclear 10, 13, 98, 348–9 potential 10, 98–9, 108–9 renewable sources of 14, 103–6 sound 10, 98, 224–34 unit of 35–8, 97–9, 110, 266–7 energy crisis 13, 104–7, 349 energy transfers 11, 12, 98, 100–4 energy transfer diagrams 102–4, 116 equations of motion 127 equilibrium 93 evaporation 56 examinations 386–7 expansion, of gases 24, 30 of liquids 24 of solids 21–3 eye, human 200–3
f-number 199 farad 245 Faraday, Michael 274, 297, 375, 377 feedback 324 fibre optics 189, 192, 218, 314 field, electric 244 gravitational 131, 149, 153 magnetic 282, 286–7, 290 filter 220 fission, nuclear 348 Fleming’s left-hand rule 290 Fleming’s right-hand rule 296 floating 87 fluorescence 210, 212, 265 flux, magnetic 282 FM (frequency modulation) 331 focal length, of lenses 194–5 of mirrors 181 focus, principal 181, 194 force 65–71, 82–7, 97, 130, 136 balanced 84–7, 89, 128 centripetal 70–1, 134, 148, 153 electric 17, 241 gravitational 65–7, 97, 131, 149, 153 moment of 90 parallelogram of 86 free-body force diagram 87 freezing point 27, 54, 57 frequency 167, 232 friction 82–3, 89, 116, 134 fuel cell 115 fuse 268–70 fusion (melting) 53 nuclear 13, 98, 152, 156, 349
half-life 344, 352 heat, and temperature 26 energy 10, 35–8, 100–1 measurement of 35–8 unit of 35–8, 97 heat exchanger 44, 348 heat pump 56 heating effect of current 264 hertz 167 Hooke’s Law 66 hot-water system 44 hovercraft 82 ‘how Science works’ 6–7, 358–70 Hubble’s Law 158, 373 hybrid car 115 hydraulic brakes 79 hydroelectric power 15, 101, 105–6 hydrogen bomb 13, 98, 156 hydrogen fuel cell 115
G galaxy 157–9 gamma-rays 208, 210, 214, 341, 347 gas laws 29–34 gases 16–18, 24, 29–34 gears 118 Geiger 339, 342 generator, a.c. 298–300 d.c. 300 Van de Graaff 244 geo-stationary orbit 154, 155 global warming 107 gold-leaf electroscope 243, 338 gravitational field 131, 149, 153 gravitational potential energy 11, 108 gravity 65–7, 85, 89, 128, 131, 153 greenhouse effect 48, 106–7, 150 grid system (national) 303 guitar 305
I ideas and evidence 358–9, 370–9 illusions, optical 201, 203 images, curved mirror 181–2 in lenses 194–6, 198 plane mirror 178 real 174, 195, 198 virtual 179 immersion heater 50, 264 inclined plane 118 induced charges 242 induced current 296–305 induction, electromagnetic 296–303 electrostatic 242 magnetic 283 inertia 68–9 infra-red rays 40, 46–51, 209, 211, 213, 214 ink-jet printer 315 insulation 12, 41–3, 51 internal combustion engine 114 internal energy 26, 35–6 inventions 378–9 inverse square law 153, 214, 217, 341 ion 244, 274, 338 ionisation 244, 338, 346 ionosphere 211 isotope 343, 346
J jet engine 114 joule 12, 35–8, 97–9, 102–9, 261, 266–7, 371 397
K Kelvin scale 27, 31 Key Skills 376–7 kilogram 9, 68, 130 kilowatt-hour 267 kinetic energy 10, 98–9, 109, 137 kinetic theory of gases 16, 34 Kirchhoff’s Law 251
L lamp, electric 103, 212, 259, 265 laser 193, 306 laser printer 315 latent heat, of fusion 53–4 of vaporisation 55 LDR 192, 319, 324, 329 LED 192, 265, 318 left-hand rule, Fleming’s 290 lenses 194–6, 198 Lenz’s Law 297 levers 90, 117 light-dependent resistor 192, 319, 324 light waves 169, 171, 207, 208 light-year 157–8, 171 lightning 227, 245 lines of force (flux) 282, 286–7 logic gates 326–9 longitudinal waves 146, 166, 225 loudness 230, 232, 234 loudspeaker 291
M machines 116–20 magnetic effect of a current 286 magnetic field 282, 286–7, 289 due to a coil, solenoid 287 magnetic induction 283 magnetic line of force (flux) 282 magnetic materials 283 magnetism, Earth’s 282 induced 283 theory of 283 magnification 195 magnifying glass 196 mains, house circuit 265, 268–70 Maltese cross tube 309 manometer 80 mantle, Earth’s 146 mass 9, 68, 130 critical 348 mass number 343 mathematics 390–1 matter, three states of 17, 18 medical physics 346, 356–7
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melting point 57 and impurities 57 and pressure 57 meteors 152 microphone 289, 291, 297, 301 microscope 196 microwaves 209, 211, 213, 216–17 microwave oven 213 mirage 189 mirror, concave 48, 181–2 convex 181–2 plane 176–9 mobile phones 216–7, 314 molecules 16, 18, 24, 26, 34, 41, 53, 56, 73, 80, 149, 225, 227, 283 moments, principle of 90–1 momentum 136–8 Moon 65, 71, 131, 149, 173 motor, electric 290–3 MRI imaging 357 multiplexing 219
N near Earth objects (NEOs) 152 nebula 152, 157 neutral point 282 neutron 342–3 neutron star 157 newton 67, 130 Newton, Sir Isaac 65, 69, 84, 130, 206, 372, 374, 376 Newton’s First Law 69–70, 128 Newton’s Second Law 130–1, 136 Newton’s Third Law 84–5, 160 noise 219, 234 NOT gate 327 nuclear energy 10, 13, 98, 348 nuclear equations 345 nuclear fission 348–9 nuclear fusion 13, 98, 152, 156, 349 nuclear reactor 104, 348–9 nucleon 343 nucleus 242, 342 nuclide 343, 345, 346
O Øersted, Hans Christian 286 ohmic conductor 253, 259 Ohm’s Law 253–5, 259 optical fibre 189, 192, 218, 314 OR gate 326–9 oscilloscope 232, 310–11, 317 oximeter 356 ozone layer 210, 214
P parachute 89, 128 parallel circuits 251, 257, 261 parallelogram of forces 86 pascal 77 pendulum 9, 99 penumbra 172–3 period, periodic time 167 periscope 177 persistence of vision 201 PET scanning 357 photocopier 315 pitch of sound 232 plane mirror 176–9 planets 150–1, 152 plug, three-pin 270 polarised waves 167 pole, magnetic 280 positron 357 potential difference 252–3, 261 potential divider 258, 318, 323, 329 potential energy 10, 98–9, 108–9 potentiometer 258 power 110–11, 135, 266–7 power station 13–15, 101, 104–6, 349 pressure 77–81 atmospheric 80 pressure cooker 57 pressure gauges 80 pressure law 32–4 principal focus 181, 194 prism, refraction by 207 totally reflecting 188 projector, optical 196, 204 proton 242, 342–3 pulleys 119 pulse oximetry 356
Q quality of sound
233
R radar 211, 311 radiation, alpha, beta 340, 345 dangers of 214, 216–17, 350 gamma 208, 210, 214, 341, 345, 347 infra-red 40, 46–51, 209–14 ultra-violet 208, 210, 212, 214 X- 208, 210, 212, 214, 312 radioactive dating 347, 352 radioactive decay 343–5, 352 radioactivity 338–52 radionuclide (radioisotope) 343, 345–6 radio telescope 159, 215 radio waves 169, 209, 211, 314, 331
RAM 314 ratemeter 339 ray, cathode 309 light 171, 176 reaction time 83, 132 reactor, nuclear 348–9 real image 174, 195, 198 rectification 316–17 red-shift 158, 373 reed relay (switch) 320 reflection, law of 168, 177 of sound 226, 228–9 total internal 187–90, 192 refraction 168, 184–7, 207, 239 refractive index 185–7 refrigerator 56 relay, electromagnetic 289, 320–1 reliability of evidence 7, 359, 361 renewable energy 14, 103–6 residual current circuit-breaker (RCCB) 272 resistance 249, 253–7, 259 measurement of 255, 259 resistors 255–7 in parallel 257, 261 in series 256, 261 resonance 231 resultant force 86–7, 89, 130 reverberation 234 revision 382–5 rheostat 255 right-hand rule, Fleming’s 296 ring main circuit 265, 268–70 ripple tank 167–9 road safety 69, 83, 138 rocket engine 85, 138, 160 rocks, dating 347, 352 Rutherford, Lord 342, 372, 377
S safety belts 69, 83, 138 Sankey diagram 102–4, 116 satellites 48, 153, 154–5, 211, 223 scalars 86 scanning 211, 229, 312, 346, 357 seismic waves 146–7, 373 semi-conductor 316 series circuits 250, 256, 261 SETI, search for life 159 shadows 172 Snell’s Law 185 solar cell 14, 103, 105, 115 solar heating 14, 48, 50, 156 solar system 150–1, 152 solenoid 287–9
sound, frequency 225, 228, 230–1 loudness of 232, 234 pitch 232 quality of 233 reflection of 226–7, 228–9 refraction of 239 speed of 225, 227, 228 sound waves 169, 225 space travel 160–1 spark counter 339 specific heat capacity 37–8 specific latent heat, of fusion 53–4 of vaporisation 55–6 spectacles 174, 196, 202–3 spectrum, electromagnetic 207–215 visible 206–7 speed 122 of light 171, 185, 208 of sound 227 speed–time graphs 89, 123–5, 135 sports 134–5 spring balance 66–7 stability 93–5 standard atmospheric pressure 80 star 152, 156–7 static electricity 241–7 steam engine 100–1 stopping distance 83 strain (elastic) energy 10, 98, 108 stroboscope 135 Sun 70, 148, 152, 156–7, 173 Sun protection factor (SPF) 214 supernova 157 switch, two-way 265 synthesizer 233
T tape recorder 283, 307 telecommunications 192, 218, 314 telephone 216, 218, 289, 314 telescopes 215 television 169, 183, 209, 211, 221, 307, 309–11 temperature 26–7 terminal velocity 89, 128 thermal energy 10, 26, 35–7, 98 thermionic emission 308 thermistor 218, 259, 319, 323, 329 thermographs 50, 211, 212–13 thermometers 26–7, 218, 254, 319 thermos flask 49 thermostat, electric 23 thinking distance 83 tides 15, 149 transducers 318, 321
transformer 301–3 transistor 322–5 transmutation of elements 345 transverse waves 146, 166, 171 truth tables 326–9
U ultrasound (ultrasonic) 226, 228–9 ultra-violet rays 208, 210, 212, 214 umbra 172–3 universe, expanding 158, 373 upthrust 87 U-values 43
V vacuum flask 49 validity of evidence 7, 359 valve, diode 308 variables 7, 360–4 Van de Graaff generator 244 vapour, water 56 vectors 86 velocity 122 of electromagnetic waves 208 of light 171, 185, 208 of sound 227 velocity–time graphs 89, 123–5, 135 vibrations 224 volt 252, 261 voltage divider 258, 318, 323, 329 voltameter 273 voltmeter 252 volume, measurement of 75
W watt 110, 266 wavelength 167 of electromagnetic waves 208–9 of light 207, 208, 210 of sound 225 waves 166–9, 207–11, 225, 311 weight 65, 67, 97, 131 weightlessness 68, 153, 160 wheel and axle 118 winds 14, 45, 103, 106 wind turbine 14, 103, 106 work 97, 99, 110
X X-rays
208, 210, 212, 214, 312
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Photograph acknowledgements AEA Technology: 346T, 350; Air Pictures: 169; Alex Segre/Alamy: 182TL; Bettmann/Corbis: 377B; Blind Mobility Research Unit Nottingham: 228B; Bosch: 293; BoxMag Rapid: 288; British Aerospace: 51BR, 189B; British Rail Research: 22; Burstein Collection/Corbis: 371T; Photoshot/Bruce Coleman: 213TL; Camera Press: 376B; Castle Associates: 234; Colorsport: 95TL, 108B, 134R, 135T, 135BR, 137; Corbis: 64BR Eddy Lemaistre/Photo & Co, 138T Parrot Pascal, 215T, Jonathan Blair, 356B Lester Lefkowitz; Corel (NT): 6 C418, 42L C127, 106 C94, 114T C62, 122 C494, 208C C285; Digital Vision (NT): 4B, 150, 173, DV9, 82 DV13, 109 Karl Ammann DVAA, 128T DVXA, 149 DV6; Elcomer Instruments: 284; Fischer Scientific: 255; Ford Motor Company Ltd: 89; Format Photography: 389BL Brenda Prince, 389TL Maggie Murray; FLPA/Nigel Catlin: 361; GEC: 300; Getty Images: 64TR, 70, 95BR, 108T, 125, 128B, 130, 135BL; 291 John Stanton; iStock: 13, 42R, 47L, 71, 79, 114B, 116, 120, 138B, 182TC, 199C, 199B, 199A, 209D, 228T, 240ML, 240BL, 240T, 252T, 260, 297, 306B, 309, 314, 315T; Joel Finler Collection: 201; John Bailey: 217T; Keith Johnson: 12, 64bl, 172, 174, 180, 188, 196, 199D, 199E, 220, 338T; Last Resort Picture Library: 83B; Leyland DAF: 97; London Buses: 95BL; London Fire Brigade: 213TR; Martyn Chillmaid: 49, 86, 105, 182TR, 184, 186, 204, 203, 209A, 213BC, 213BR, 229B, 232, 245, 250L, 250R, 252BL, 252BR, 275, 283, 302, 319T, 319B, 325, 327, 331, 339, 344; Mary Evans Picture Library: 47BR, 95TR; 373BL Alamy; Barnaby’s Picture Library; MEMTEK: 231; NASA: 152, 153, 154, 158, 161T, 161BL, 161BR, 215B; National Gallery London: 212 UML, 212 UMR; National Power: 15B; National Remote Sensing Centre: 157T, 157B; Nokia: 216; OMRON: 27B; Ontario Science Centre: 244; PhotoDisc (NT): 200 PD40, 208A PD54, 208B PD18, 208E PD2, 209B PD22, 389TR PD72; Photolibrary: 146B; Racall: 311B; Ripley’s Believe It or Not!: 312B; Robert Harding Picture Library: 45, 47TR; Rolls Royce: 389BC; Royal Astronomical Society: 151; RS Components: 258; Sally & Richard Greenhill: 210B; Science and Society Picture Library: 338B, 345; Science Photolibrary: 4t Dr Mitsuo Ohtsuki, 14T, 311T, 312TL, 371B, 374BL, 375B, 376TR SPL, 14B, 50T, 103B, 115T Martin Bond, 27T Chris Priest & Mark Clarke, 46L, 51BL, 182B, 212B, 217B, 240MR, 347T, 250B Cordelia Molloy, 46R Martyn F
Chillmaid, 50BL Dr Ray Clarke & Mervyn Goff, 51TR Dr Ray Clark, 64TL Alex Bartel, 104T Kaj R. Svensson, 103T Tony Wood, 115M Peter Menzel, 127 Renee Lynn, 134L Jerry Wachter, 156, 159T, 160, 213BL, 352T NASA, 159B Robin Scagell, 155T David Ducros, 155BL, 155BR, 146T NRSC Ltd, 166 Martin Dohrn, 173B George East, 182TL Francoise Sauze, 189T Edelmann, 192 Steve Horrell, 193 Rosenfeld Images Ltd, 206 Simon Fraser, 207 Fred Burrell, 210T Martin Dohrn, 210M Phillipe Plailly, 211T Dr R. Clark & M.R. Goff, 211B Agema Infrared Systems, 212TL Erich Schrempp, 212TC Phil Jude, 212lML, 212lMR, 267, 268R, 268C, 268L, 270, 374T, 375TL, 376TL Sheila Terry, 229T Saturn Stills, 229UM Cnri, 229LM Alexander Tsiaras, 306T Dr Jeremy Burgess, 312TR Stammers/Thompson, 346BL 346BR Elscint, 347B Gianni Tortoli, 348T Hank Morgan, 356T David Parker, 356M James Prince, 357T Geof Tompkinson, 357B Hank Morgan, 358 Samuel Ashfield, 372T Adam Hart-Davis, 372B National Library Of Medicine, 374M Emilio Segre Visual Archives/American Institute Of Physics, 374BR Sam Ogden, 375TR Jean-Loup Charmet, 377TR Physics Today Collection/American Institute Of Physics, 389BL James King-Holmes, 389ML Volker Steger, 389 BR Physics Department/Imperial College London, 389MC Mauro Fermariello, 389MR Maximilian Stock Ltd; Scottish Power: 15T; Shell: 74; Spectrum Colour Library: 53; Stone/ Getty Images: 104B; The Print Collector/Alamy: 377TL; Time & Life Pictures/Getty Images: 373BR; Topfoto.co.uk: 83T, 115B Rachel Epstein; Transport Research Laboratory: 69T USGS: 373T; Volvo: 69B; Yamaha: 233; ZEFA: 135M, 212TR. Every effort has been made to trace and contact all copyright holders, but if any have been overlooked, the publisher will be pleased to make the necessary arrangements at the first opportunity. Picture research by
[email protected] and Sue Sharp Illustrations by IFA Design Ltd, Tony Wilkins Illustration, Jordan Publishing Design, Jane Cope and Ann Johnson
Thanks to Chris and Rachel Johnson for checking the answers section. Acknowledgement is also made to the following Examining Groups for permission to reprint questions from their examination papers. The questions are not necessarily from examinations for the current specification but are believed to be relevant. The Examining Groups do not take responsibility for the answers provided. AQA Assessment and Qualifications Alliance NIS Northern Ireland Schools Examinations Council Edex Edexcel Foundation WAEC West African Examinations Council OCR Oxford, Cambridge and RSA Examinations WJEC Welsh Joint Education Committee Cam IGCSE University of Cambridge Local Examinations Syndicate (Cambridge IGCSE Physics Paper 6 Nov 06 Q2; Nov 08 Q2) Edex IGCSE Edexcel IGCSE Examinations Websites : www.physicsforyou.co.uk and www.physics4u.co.uk From these you can download exactly which pages in this book you need to study for your particular examination course.
Other books by Keith Johnson Advanced Physics for You with Simmone Hewett, Sue Holt, and John Miller This is written in the same friendly style as the GCSE book, and covers the core of AS and A-level Physics, with over 200 worked examples. Timetabling: A Timetabler’s CookBook This book is a complete and practical guide for those staff responsible for timetabling in schools.
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Spotlight Science 7, 8 and 9 with Sue Adamson, Gareth Williams, Lawrie Ryan This is a flexible and accessible science course for KS3, for students at all attainment levels. The Teacher’s Support Packs contain an enormous amount of valuable support material to support differentiation in your teaching and learning. There are 2 versions : the original ‘Spiral’ version and the newer ‘Framework’ version.
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