Table Of ContentAQA
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A-Level Physics l
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for AQA: Year 1 & AS-Level
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This CGP book is a comprehensive guide to success in A-Level Year 1 and AS-Level P Exam Board: AQA
Physics for AQA. h
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Fully up to date for the new A-Level courses from 2015 c
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Straightforward explanations with no unnecessary jargon
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Practice questions and exam-style questions in every section h
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In-depth advice on maths skills, practical investigations and more C
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A free Online Edition to read on your PC, Mac or tablet m
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And since it’s a CGP book, it covers everything you need as painlessly as possible. e
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May contain traces of knowledge
Y1
The Complete Course for AQA
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AS / Year 1
Physics
The Complete Course for AQA
Let’s face it, Physics is a tough subject. You’ll need to get to grips with a lot of
difficult concepts, and have plenty of practical skills up your lab-coat sleeve.
But don’t worry — this brilliant CGP book covers everything you’ll need for
the new AQA courses. It’s packed with clear explanations, exam practice,
advice on maths skills and practical investigations... and much more!
Contents
Section 3: Waves
Introduction
1. Progressive Waves 65
How to use this book i 2. Wave Speed 69
3. Transverse and Longitudinal Waves 72
4. Superposition and Interference 77
5. Stationary Waves 80
Practical Skills Practical 6. Investigating Resonance 84
skills
7. Diffraction 86
1. Experiment Design 1
8. Two-Source Interference 89
2. Data 4
9. Young’s Double-Slit Experiment 92
3. Graphs 6
10. Diffraction Gratings 96
4. Error Analysis 9
11. Refractive Index 100
5. Uncertainty Calculations 12
12. Critical Angle and TIR 103
6. Evaluating and Concluding 15
Exam-style Questions 108
Section 4: Mechanics
Sections
1. Scalars and Vectors 111
2. Forces in Equilibrium 115
Section 1: Particles and Radiation
3. Moments 118
1. Atomic Structure 17
4. Centre of Mass and Moments 121
2. Stable and Unstable Nuclei 21
5. Uniform Acceleration 123
3. Antiparticles and Photons 25
6. Displacement-Time Graphs 125
4. Hadrons and Leptons 29
7. Velocity-Time Graphs 130
5. S trange Particles and Conservation
8. Acceleration-Time Graphs 135
of Properties 33
9. Newton’s Laws of Motion 137
6. Quarks and Antiquarks 36
10. Acceleration Due To Gravity 139
7. Particle Interactions 40
11. Projectile Motion 143
Exam-style Questions 46
12. Drag, Lift and Terminal Speed 145
13. Conservation of Momentum 149
Section 2: Electromagnetic 14. Force, Momentum and Impulse 152
Radiation and Quantum Phenomena 15. Work and Power 156
1. The Photoelectric Effect 49 16. Conservation of Energy 160
2. Energy Levels in Atoms 54 Exam-style Questions 166
3. Wave-Particle Duality 58
Exam-style Questions 63
Section 5: Materials
Maths Skills Maths
skills
1. Density 170
2. Hooke’s Law 171 1. Calculations 221
3. Stress and Strain 175 2. Algebra 226
4. The Young Modulus 179 3. Graphs 228
5. S tress-Strain and Force-Extension Graphs 181 4. Geometry and Trigonometry 233
6. Brittle Materials 184
Exam-style Questions 187
Exam Help ExaM
HELP
Section 6: Electricity
1. Circuit Diagrams 189 Exam Structure and Technique 235
2. Current and Potential Difference 190
3. Resistance 192
4. I-V Characteristics 194
Reference
5. Resistivity 197
6. D etermining the Resistivity of a Wire 200
Answers 238
7. Power and Electrical Energy 202
Glossary 263
8. E.m.f. and Internal Resistance 205
Acknowledgements 269
9. Conservation of Energy and
Index 270
Charge in Circuits 209
Data Tables 274
10. The Potential Divider 214
Exam-style Questions 218
How to use this book
Learning Objectives Learning Objectives: 3. Wave-Particle Duality
Understand that
These tell you exactly what you need to ewlaevcetrso cmaang bneehtiacv e Tbhuet tphheoreto’se plelecntrtiyc oeff feevcitd (esnecee p tahgaet 4it9 a)c stsh oaws as twhaavt eli gtohot .c aInt taucrnt sa so ua tp tahrattic nleo,t
as particles, and only can waves act like particles, but particles can also act like waves.
learn, or be able to do, for the exams. particles can show
wave-like properties. Is light a particle or a wave?
Be able to understand
There’s a specification reference at the and calculate the Diffraction
de Broglie wavelength When a beam of light passes through a narrow gap, it spreads out.
bottom that links to the AQA specification. oλf =a pmahrvti,c le, given by Twhaivse iss. c Iafl ltehde dliigfhfrta wctaios na c(stieneg pa.s8 6a )p. a Drtiifcflrea,c tthioen l icgahnt poanrltyi cblees e ixnp tlhaein beeda umsi ng
where mv is the would either not get through the gap (if they were too big), or just pass
momentum. straight through and the beam would be unchanged.
Know that our
understanding of
the nature of matter
changes over time,
as new theories slit
are evaluated and light beam
validated by the
scientific community.
Exam Tips Uelnecdterorsnta dnidff rtahcatti on screen
suggests the wave
nature of particles. Figure 1: Diffraction of light waves as they pass through a narrow slit.
There are tips throughout Be able to explain
how and why
diffraction changes The photoelectric effect
the book to help with all when the momentum The results of photoelectric effect experiments (see p.49) can only be
of a particle changes. explained by thinking of light as a series of particle-like photons. If a photon
sorts of things to do with ReSfepreecnificcea 3t.i2o.n2 .4 oofn lei-gthot- oisn ea wdiascy.r e Atel lb tuhne delnee orgf ye nine rtghye, tphheont oitn c iasn g iinvetenr atoct ownieth e laenc terloenc.tron in a
answering exam questions. The photoelectric effect and diffraction show that light behaves as
Exam Tip both a particle and a wave — this is an example of a phenomenon known as
Make sure you know wave-particle duality.
the two examples that
sah wowav eli gahntd a ac tps aarst ibcolet h Wave-particle duality theory
— they might just Louis de Broglie made a bold suggestion in his PhD thesis. He said
come up in the exam. if ‘wave-like’ light showed particle properties (photons), ‘particles’
like electrons should be expected to show wave-like properties.
Tips Tmmveioaplosm:s c eiRmtnyeut muoltmfei pam linisbe otedhbr e bjte hyc attth. e moving pTahreti cdlee Bprroogpleiert ye q(muaotimonen rteulmate, sm av )w. a ve property (wavelength, l) to a
These are here to help you Tthiep :d eT hBer odgelrieiv aetqiounat ioofn lw a=v delee nBgrothg liine m λ =mhv h == t6h.e6 3P l×a n1c0k– 3c4 oJsn.stant
understand the theory. itnshe ibese dcy otooun rwdse ot,hr rseyo s aycboooupu edt ooitfn. ’t m = mass in kg v = velocity in ms–1
58 Section 2 — Electromagnetic Radiation and Quantum Phenomena
Searching for particles
As time goes on, our knowledge and understanding of particle physics
changes. Sometimes, physicists hypothesise a new particle and the properties Examples
they expect it to have, in order to explain observations from experiments. For
example, the neutrino was hypothesised due to observations of beta decay.
Experiments to try to confirm the existence of this new particle are These are here to help you
then carried out. Results from different experiments are combined to try to
confirm the new particle. If it exists, the theory is more likely to be correct, understand the theory.
and if there are no other reasons to doubt the existence of the particle, then
the scientific community start to accept the theory, meaning it’s validated.
However, experiments in particle physics often need particles
travelling at incredibly high speeds (close to the speed of light). This can only
be achieved using particle accelerators, which are very expensive to build and
run. This means that large groups of scientists and engineers from all over the
world have to collaborate to be able to fund these experiments. Practice Questions — application
Example thFeig Eunrgel i1sh0: p hPyasuilc iDsti rwach,o
Currently, scientists are trying to figure out why there is more matter predicted the existence of Annoyingly, the examiners expect you to
than antimatter in the Universe. They are doing this by studying the antimatter.
dLpaiafrrfgteierce lHne caaedcsrc oiennle bCraeothollarivd cieoorus (trLi noHgfC ma)r aaottut eCnrdE aR £nN3d. ba Tnilhtliiemo nLa HtttoeC rb ipus aialrd t1i ca7ln emds iu£les1i 5nlo gmn tgihl lei on Thyipp:o tPhaeusils Dedir athce be able to apply your knowledge to new
per year to run. Some 10 000 scientists from 100 countries are involved. existence of antimatter situations — these questions are here to
in 1928. His theory
wthaes o vbasleidrvaatetido nw oitfh t he give you plenty of practice at doing this.
Practice Questions — Application positron, along with
Q1 Calculate the charge and strangeness of the other antiparticles. All the answers are in the back of the
following quark compositions.
a) uu book (including any calculation
b) uus
c) dss workings).
d) sss
Q2 A lambda particle L0 is a baryon with strangeness –1.
Using any of u, d and s quarks (and their antiparticles),
write down its quark composition.
Practice Questions — Fact Recall Practice Questions — Fact Recall
Q1 Name three quarks.
Q2 What is the baryon number of a quark? There are a lot of facts you need to
Q3 What is the strangeness of a strange quark?
Q4 Write down the quark composition of a: learn — these questions are here
a) proton b) neutron c) antineutron
Q5 What is the quark composition of a meson? to test that you know them.
Q6 Why can you not have a quark on its own?
Q7 What sort of interaction can change a quark’s character? Name and
describe an interaction in which this happens. All the answers are in the back of
the book.
Section 1 — Particles and Radiation 39
i
Required Practicals
Investigating the double-slit formula REQUIRED 2 There are some key practicals that you’ll be
You can investigate this formula using the double-slit PRACTICAL
apparatus on pages 92-93. You’ll need to measure D
and w using a ruler, and s should be printed on the double slit. expected to do throughout your course. You’ll need
Since the wavelength of light is so small, you can see from the formula
that a high ratio of D/s is needed to make the fringe spacing big enough to to know all about them for the exams. They’re all
see. Rearranging, you can use l = wDs to calculate the wavelength of the light.
Tsreeidpveu: rc aMel tfehraiens uguernisnc wge riatlacl irnotsys. vnaulmueb eorf Towhf .ef r Iiftnr’sign eeg aewssii edarrt heto su bmsueetawalsleyue rsneo atthcineryom st.sh aset vite’sr avle frryin hgaersd t htoe ng edti vaind ea cbcyu trhaete marked up throughout the book with stamps.
Ew.gid. tihf yoof uo nmee farisnugree tahse Example Maths Skills
1.0 ± 0.1 cm, then the The maxima of an interference pattern produced by shining a laser
percentage uncertainty light through a double slit onto a screen is shown in Figure 6. Practical Skills
is 10%. But if you The slits were 0.20 mm apart and the distance between the slits
mfrienagseusr aes t h1e0 .w0 i±d t0h. 1o fc 1m0, and the screen was 15.0 m. Find the wavelength of the laser light.
then the average fringe 0.28 m There are some key practical skills you’ll not
width is 1.0 ± 0.01 cm
(aynodu tdhiev iudnec tehreta rinestyu lbt y only need to use in your required practicals,
the number of fringes),
suon ctheert apienrtcye ins toangely 1.0%. Figure 6: A double-slit interference pattern. but you could be tested on in the exams too.
Y(lo)u. cBaunt firerastr ryaonug en Yeoedu ntog’ sfi dnodu tbhlee -frsilnitg feo rsmpauclain tgo ofifn odn teh fer iwngaev e(wle)n. g th There’s a practical skills section to cover these
Seven fringe widths in figure 10 have a spacing of 0.28 m, so one
Tip: Don’t get confused fringe width has a spacing of 0.728=0.040m. skills at the front of the book.
hs7pe goraetsp. s (Tm (hfareixrneigm eaa rwe), i8bd utbhtr sio)g nhlty Rwe =ar 0ra.n0g4e0 tmhe, sfo =rm 0u.0la0 0a2n0d msu banstdit uDte = i n1 5th.0e min.formation you know:
bnweeitedwdthe t eobn yd t7ihv eiadmned. t hnSeoo t t yo8ot.aul w=lsD&l=wDs=0.040#150.00020=5.3#10-7m(to2s.f.) Maths Skills Examples
You can investigate a range of relationships using Young’s double-slit
experiment. Try: There’s a range of maths skills you could
Varying D to see how it affects w.
Varying s by using different double-slit systems to see how it affects w. be expected to apply in your exams.
Varying the wavelength/colour of the light to see how it affects w.
You should find that all of these change w in line with w=lsD. Examples that show these maths skills
Figure 7: Coloured lenses
can be used to limit the
range of wavelengths from a Evidence for the wave nature of light in action are marked up like this.
light source.
Towards the end of the 17th century, two important theories of light were
published — one by Isaac Newton and the other by a chap called Huygens.
Newton’s theory suggested that light was made up of tiny particles, which he
Tdiispc:o vIte wreads tlhaatet rl ight has called “corpuscles”. And Huygens put forward a theory using waves.
properties of both waves The corpuscular theory could explain reflection and refraction, but Maths Skills
and particles. See pages diffraction and interference are both uniquely wave properties. If it could
58-61 for more on wave- be shown that light showed interference patterns, that would help settle the
particle duality. argument once and for all. There’s a whole maths skills section
94 Section 3 — Waves on pages 221-234 that’s packed
with plenty of maths you’ll need to
need to be familiar with.
Exam-style Questions
Practising exam-style questions is really
important — you’ll find some at the end of
Exam-style Questions
each section.
They’re the same style as the ones you’ll 1 A materials scientist carried out an investigation to find how the extension of a
rubber cord varied with the forces used to extend it. She measured the extension
get in the real exams — some will test for an increasing load and then for a decreasing load. The graph below shows her
results. Curve A shows loading and curve B shows unloading of the cord.
your knowledge and understanding and
40
some will test that you can apply your
30
kAnllo twhele adngsew. ers are in the back of the book, Force (N)20 A B
10
along with a mark scheme to show you
how you get the marks. 00 0.10 0.20 0.30 0.40 0.50
Extension (m)
1.1 State the feature of the graph that shows that the rubber cord is elastic.
(1 mark)
1.2 The rubber cord has a cross-sectional area of 5.0 × 10–6 m2 and had an initial length
of 0.80 m.
Exam Help Amsosduumluins gfo trh atht ec ururvbeb eAr ims alinteeraiar l ffoorr asnm eaxllt elonasdiosn. oGf i0ve.0 y8o0u mr a, ncaswlceurla itne Pthae. Young
(2 marks)
There’s a section at the back of the book stuffed
full of things to help with your exams. 2 A spring is used in a pen as part of the mechanism which opens and closes it.
For small loads, the spring obeys Hooke’s law.
2.1 Define Hooke’s law.
(1 mark)
2.2 The spring constant for the spring is 650 Nm–1.
Calculate the distance that the spring is compressed when a user pushes it down
with a force of 0.90 N.
Glossary (2 marks)
2.3 The spring must not be compressed more than 0.020 m.
Calculate the maximum force that can be applied to the spring.
There’s a glossary at the back of the book full
(2 marks)
of all the definitions you need to know for
the exam, plus loads of other useful words.
Section 5 — Materials 187
ii
Published by CGP
Editors:
Emily Garrett, David Maliphant, Frances Rooney, Charlotte Whiteley, Sarah Williams, Jonathan Wray.
Contributors:
Jane Cartwright, Peter Cecil, Mark A. Edwards, Barbara Mascetti, John Myers, Andy Williams.
PATB52DK
With thanks to Simon Whiteley for the image on page 10.
With thanks to Ian Francis, Sam Pilgrim and Glenn Rogers for the proofreading.
With thanks to Jan Greenway for the copyright research.
Clipart from Corel®
Text, design, layout and original illustrations © Coordination Group Publications Ltd. (CGP) 2015
All rights reserved.
0800 1712 712 • www.cgpbooks.co.uk
Practical Practical Skills
skills
1. Experiment Design
Before you can even think about picking up some apparatus, you need to
design every aspect of your experiment. The information on these pages
should help you answer questions on experimental methods in the exam.
Planning experiments
Tip: You might be
Scientists solve problems by asking questions, suggesting answers and asked to design a
then testing them to see if they’re correct. Planning an experiment is an physics experiment to
investigate something or
important part of this process to help get accurate and precise results
answer a question.
(see p.15). There’s plenty of info on the next few pages, but here’s a
summary of how you go about it... It could be a lab
Make a prediction — a specific testable statement about what will experiment that
happen in the experiment, based on observation, experience or a you’ve seen before, or
something applied, like
hypothesis (a suggested explanation for a fact or observation).
deciding which building
Think about the aims of the experiment and identify the material is best for a
independent, dependent and control variables (see below). particular job. Either
Select appropriate equipment (see next page) that way, you’ll be able to
use the physics you
will give you accurate and precise results.
know and the skills
Do a risk assessment and plan any safety precautions (see p.3).
in this topic to figure
Decide what data to collect and how you’ll do it (p.4-5). out the best way to
investigate the problem.
Write out a clear and detailed method — it should be clear enough
that anyone could follow it and repeat your experiment exactly.
Carry out tests — to provide evidence that will
support the prediction or refute it.
Variables
You probably know this all off by heart but it’s easy to get mixed up
sometimes. So here’s a quick recap.
A variable is a quantity that has the potential to change, e.g. mass.
There are two types of variable commonly referred to in experiments:
Independent variable — the thing that you change in an experiment. Tip: When drawing
graphs, the dependent
variable should go on
Dependent variable — the thing that you measure in an experiment. the (vertical) y-axis,
and the independent
It’s important to control the variables in an experiment. Keeping variable on the
all variables constant apart from the independent and dependent variables, (horizontal) x-axis. The
means that the experiment is a fair test. main exceptions to this
are load-extension (or
This means you can be more confident that any effects you see are
force-extension) and
caused by changing the independent variable. The variables that are kept
stress-strain graphs.
constant (or at least monitored) in an experiment are called control variables.
Practical Skills 1
Example
You could investigate the effect of varying the voltage across a filament lamp
on the current flowing through it using the circuit shown in Figure 1 below:
V
S
Potentiometer — to alter Power supply.
Tip: For more on the voltage supplied to
potentiometers see the filament lamp from 0 V Ammeter — to measure
page 215. to the source voltage, V. A the current flowing through
s the filament lamp.
Voltmeter — to measure
Filament lamp.
the voltage.
V
Figure 1: Circuit diagram for measuring the current flowing through a filament lamp.
The independent variable will be the voltage supplied to the lamp.
The dependent variable will be the current flowing through the lamp.
For the experiment to be a fair test, all the other variables must be kept
Figure 2: The filament in a the same. These are the control variables. These include the length of
bulb is designed to heat up, the connecting leads and the filament bulb used. You might also use
so it should be allowed to small voltages (and currents) to stop the circuit wires heating up during
cool in between repeats to the experiment, and allow the filament to cool between repeats.
make it a fair test.
apparatus and techniques
You need to think about what units your measurements of the independent
Tip: Remember — and dependent variables are likely to be in before you begin (e.g. millimetres
part of choosing your or metres, milliseconds or hours).
apparatus and planning Think about the range you plan on taking measurements over too
your technique will — e.g. if you’re measuring the effect of increasing the force on a spring, you
involve thinking about
need to know whether you should increase the force in steps of 1 newton,
safety precautions. This
10 newtons or 100 newtons. Sometimes, you’ll be able to estimate what
should all be covered in
effect changing your independent variable will have, or sometimes a pilot
your risk assessment.
experiment might help.
Example
A student is investigating the extension of a test wire using the apparatus
in Figure 3. She will add weights to the wire and measure its extension
using the marker and the ruler.
wire fixed at marker
one end test wire on wire pulley
Tip: There’s more on
using this apparatus on
p.179.
bench ruler with mm markings
weights
Tip: Measuring a Figure 3: Experimental set-up for investigating the extension of a test wire.
distance that is small
She decides to do a pilot experiment to decide on the increments in which
compared to the
she should add weights to the test wire. She is aiming to find out:
resolution of your
equipment will lead to a How much weight needs to be added to cause the marker on the wire
high percentage error in to move a sensible measurable distance along the ruler.
your measurements —
How much weight would cause the wire to snap — she wants to make
see p.12.
sure she adds nowhere near that much weight in the real experiment.
2 Practical Skills
