AQA A Level Physics (Year 1 and Year 2)

608 Pages·36.796 MB·English

by  Jeremy Pollard, Carol Davenport, Nicky Thomas, Nick England

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●● Numerous stretch and extension materials to encourage higher-attaining students
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AQA
A-level
Physics
Nick England
Carol Davenport
Jeremy Pollard
Nicky Thomas
Approval message from AQA
The core content of this digital textbook has been approved by AQA for use with our
qualification. This means that we have checked that it broadly covers the specification and
that we are satisfied with the overall quality. We have also approved the printed version of this
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We approve print and digital textbooks because we know how important it is for teachers
and students to have the right resources to support their teaching and learning. However, the
publisher is ultimately responsible for the editorial control and quality of this digital book.
Please note that when teaching the AQA A-level Physics course, you must refer to AQA’s specification
as your definitive source of information. While this digital book has been written to match the
specification, it cannot provide complete coverage of every aspect of the course.
A wide range of other useful resources can be found on the relevant subject pages of our
website: www.aqa.org.uk.
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© Nick England, Carol Davenport, Jeremy Pollard, Nicky Thomas 2019
First published in 2019 by
Hodder Education,
An Hachette UK Company
Carmelite House
50 Victoria Embankment
London EC4Y 0DZ
www.hoddereducation.co.uk
Impression number 10 9 8 7 6 5 4 3 2 1
Year 2023 2022 2021 2020 2019
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Cover photo © pixbox77 - stock.adobe.com
Illustrations by Aptara
Typeset in 11/13 pt ITC Berkeley Oldstyle by Aptara, Inc.
Printed by Replika Press Pvt. Ltd. in Haryana, India
A catalogue record for this title is available from the British Library.
ISBN: 978 1 5104 6988 4
469884_FM_AQA_A-Level_Physics_i-vi.indd 2 17/04/19 8:54 AM
Contents
C
o
n
t
e
Get the most from this book v n
t
s
1 Particles and nuclides 1
2 Fundamental particles 18
3 Electrons and energy levels 42
4 Particles of light 57
5 Waves 70
6 Combining waves 95
7 Introduction to mechanics 116
8 Motion and its measurement 133
9 Newton’s laws of motion 151
10 Work, energy and power 168
11 Momentum 183
12 Properties of materials 200
13 Current electricity 221
14 Electrical circuits 244
15 Circular motion 274
16 Simple harmonic motion 285
17 Gravitation 308
18 Thermal physics 329
19 Electric fields 358
20 Capacitance 381
21 Magnetic fields 403
22 Magnetic flux 420
23 Alternating currents and transformers 435
24 The evidence for the nucleus 449
25 Radioactive decay 468
26 Nuclear energy 485
469884_FM_AQA_A-Level_Physics_i-vi.indd 3 17/04/19 8:54 AM
27 Optional topic: Astrophysics 501
28 Maths in physics 546
29 Developing practical skills in physics 571
30 Preparing for written assessments 584
Index 593
Acknowledgements 600
Go online to www.hoddereducation.co.uk/AQAPhysics
for answers.

iv
469884_FM_AQA_A-Level_Physics_i-vi.indd 4 17/04/19 8:54 AM
Get the most from this book
G
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Welcome to the AQA A-level Physics Student’s Book. This book covers all e
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content for the AQA A-level Physics specification. o
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The following features have been included to help you get the most from fr
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Prior knowledge is
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This is a short list of topics that o
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the pivot.
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AAdi rsvececactltiaoornr . qquuaannttiittyy iiss oonnee wwhhicichh h haass s sizizee o annldy. Amte masscpsa,el traearmt uqprueea rinastt 1uit9rye° ,Ci se’ ;no ientr emg ytah, kdaeti ssot annnolyc sehe, ansssp ese ietzode . s aaSnycd a‘ 1ltai9rm° qCeu. waWnetesi ttswiaeaysr itdnhsca’.ltu ‘droeo: m
A resultant vector is the vector that results A vector quantity is one that has magnitude (size) and direction. Vector
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about a speed; when you write that a car is travelling at 30 m s–1 due
east, you have used a vector quantity, which is called velocity. In a similar
way, the word displacement is used to describe a distance travelled in a
particular direction.
You have learnt to add or subtract simple vectors. In Figure 7.3 a two forces
acting in the same direction add up to make a larger resultant force of
200 N, and in Figure 7.3 b two forces acting in opposite directions make a
smaller resultant force of 300 N.
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Engineers who build bridges, or who design Formula 1 cars, need a
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Figure 7.3 (a) two forces acting in the same direction and (b) two forces acting in
opposite directions.
469884_07_AQA_A-Level_Physics_116-132.indd 116 26/03/19 8:59 PM469884_07_AQA_A-Level_Physics_116-132.indd 117 26/03/19 8:59 PM
Activities and Required
practicals
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for checking your understanding as 26/03/19 7:22 PM469884_01_AQA_A-Level_Physics_001-017.indd 9
you progress through a topic.
Tips
469884_01_AQA_A-Level_Physics_001-017.indd 8
These highlight important facts,
common misconceptions and signpost
you towards other relevant topics.
469884_FM_AQA_A-Level_Physics_i-vi.indd 5 17/04/19 8:54 AM
Practice questions
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Questions are colour-coded, to help target your pract06/0i3/19 c 9:25 PeM :
Green – Basic questions that everyone should be able to answer
without difficulty.
Orange – Questions that are a regular feature of exams and that all
competent candidates should be able to handle.
Purple – More demanding questions which the best candidates should
be able to do.
Stretch and challenge – Questions for the most able candidates to test
their full understanding and sometimes their ability to use ideas in a
novel situation.
Key terms and formulae
These are highlighted in the text
and definitions are given in the
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for the more mathematical ii) aCtatlrcaucltaivtee tohre r efoprucles ibveet?ween the spheres in this case. Is the force Ninofitnei tteh adti stthaen lciem.its of the integration set the potential as zero at an
physicists. ●●EFigluerec 1t9r.2i1c saholw ps ao stmealnl cthiaargeld isolated sphere. In theory, an isolated Adzeibfrfoseo rpeluonttceeen ebtlieaetlc,w twreihecin cp hao itpseo innintftiian alitn Tedhly ae f ppaoor itanewtn aatiyta .l pTabehsre o uflounrtitem peuollesaci ttVirvice= pc4hoπQtaεer0ngreti a ihnl e amltp aos vpuions igtno ti t dr f erforfiomnme ∞ aab tcsoho atlhrugatete p +eoQlein citst. r tNihceo p tweo ottehrnka ttd iiaofl nt. heTa ht e
sphere should be in contact with nothing and infinitely far away from charge is −Q, then the potential is negative and the electric field does work
anything else. In practice, in a laboratory, the best we can do is to suspend a in moving a positive charge closer to the point r.
sphere by a fine, insulating thread and make sure the sphere is a few metres
from everything else.
The potential at a distance r from the centre of a sphere carrying a charge Q EXAMPLE
is given by Electric field near a charged sphere V = 1000 V
 EExxaammpleps loef squestions and 5    ELECTRIC FIELDS F+iQgure 19.21isnuspuplaotrintingg t hsrrpehaedre NsTeecppxlaoheoshciecteneeest Vptrreo itet ifchf = n toaigahsflrrti4 amn aapiπtvlQifo εsut igteott0lhreala raynnteevi te oaciaigtwanhraaleaata,t ilriyvco vgp lenefeoorr. asoyitlese m s pnnti ootmeait agnaeilal yn,act trtihpivh ataleeoalr, ng mztteehehu,tre e ocso ntfa r op n atrsohl mtwbieane ruapt. y lpooIasont ffeb s opanietr ot is nivtgiaeemerln ga onitvalireatia tiarnlva retwei istg,o oa adwny t,teaih hvftlie heenpr .eece o Idhaztnsee a a nrrtashogtn ie eaa d l  – FcsAS12vCath ik nrgtrttaeeohhyusrtn eercgDawge helpf.t oei d1hoegn 9r tlrtgade.oa2 t n pt s2ahCtht iersp asie hslo lnti oton1egw 0entssh 0htA i0aoa t0 wlom Vo hB fem ot 1aaw−0n1l0 .ds0p tVhh. eeTrnhe ef or oef lmreac dtriuics fi1e0l cdm , Fig–u50rA ec m19.22 –101B c0mV00/V0E1/V0100mC0 c–01m 50D cm
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●● EE iiss aco vnencetocrte, dso t om tuhset pcohtaenngtiea ld birye tchtieon. –1000 E–/1V0m00–01
equation E=−ddVr. On the right-hand Figure 19.23
AQA has provided five optional topics as part of the full A-level course so students can focus on their areas of
interest: Astrophysics, Medical physics, Engineering physics, Turning points in physics, and Electronics. A chapter covering
the first optional topic, Astrophysics, has been included in this book (Chapter 27).
Dedicated chapters for developing your Maths and Practical skills and Preparing for your exam can be found at
the back of this book.
469884_FM_AQA_A-Level_Physics_i-vi.indd 6 17/04/19 8:54 AM
1
Particles and nuclides
PRIOR KNOWLEDGE
● Matter is made of atoms. Atoms are made up of a very small central
nucleus containing particles called protons and neutrons, surrounded
by orbiting electrons. The number of protons contained in the nucleus
of an atom is called the proton or atomic number and the total number
of protons and neutrons is called the nucleon or mass number.
● Protons are positively charged particles with a relative charge of +1;
electrons are negatively charged particles with a relative charge of −1;
neutrons are electrically neutral with a relative charge of zero.
● Atoms are electrically neutral overall, which means that they have
the same number of protons and electrons. When atoms lose or
gain electrons they become ions. An excess of electrons produces a
negatively charged ion whereas a shortage of electrons produces a
positively charged ion.
● The diameter of an atomic nucleus is of the order of 10 000 times
smaller than the diameter of an atom, but contains the vast majority
of the atomic mass. Protons and neutrons have a relative mass of 1,
with electrons about 1800 times less massive.
● Elements are made up of atoms with the same proton number. Atoms
can have the same number of protons but different numbers of
neutrons: these are called isotopes.
● The relative atomic mass of an element compares the mass of atoms
of the element with the carbon-12 isotope.
TEST YOURSELF ON PRIOR KNOWLEDGE
1 Naturally occurring hydrogen has three isotopes: (‘normal’) hydrogen,
deuterium and tritium. What three properties do atoms of each of
these isotopes have in common? How do the isotopes differ?
2 What is the relative charge of a copper atom that has lost two
electrons?
3 Chlorine has two naturally occurring isotopes that exist in an almost
75 : 25 abundance ratio. The average relative atomic mass of chlorine
is 35.5. What are the relative atomic masses of these two isotopes?
Find out their proton and nucleon numbers.
4 As at spring 2019, the element with the highest atomic number so far
discovered is ognasson (Og, atomic number 118), first synthesised in
1
2002, of which only five or six atoms have been observed, each with a
relative atomic mass of 294. Determine its:
a) proton number
b) neutron number
c) electron number
d) proton : electron mass ratio.
469884_01_AQA_A-Level_Physics_001-017.indd 1 17/04/19 8:57 AM
On 8th October 2013 the Nobel Prize in Physics was awarded jointly to
François Englert and Peter Higgs for the theoretical discovery of the particle
known as the Higgs Boson. (This followed its experimental discovery by
the Large Hadron Collider team at CERN on 4th July 2012). This discovery
completes our current best model of what the Universe is built from, called
the Standard Model, a model that started development nearly two and a half
thousand years ago by a Greek philosopher called Democritus.
Figure 1.1 Peter Higgs and the Higgs
Boson Theory. It is said that Democritus observed that the sand on a beach was once part
of the rocks of the cliffs and he questioned whether the sand could be cut
into ever smaller pieces by a succession of sharper and smaller knives. It
was Democritus who first coined the word ‘atom’, meaning the smallest
indivisible piece that the sand could be cut up into. Nearly 2500 years later,
JJ Thomson was able to extend Democritus’ thought experiment when he
discovered the electron, splitting up atoms and discovering the first sub-
atomic particle.
In the early 1980s, researchers at IBM in Zurich produced a machine
called an atomic force microscope that was able to image individual atoms.
Figure 1.2 A more recent image taken
Figure 1.2 shows a more recent image taken by a transmission electron
by a transmission electron microscope
showing individual gold atoms each microscope showing individual gold atoms. Each individual gold atom is
separated from its neighbour by a separated from its neighbour by a distance of 2.3 nm (2.3 × 10−9 m).
distance of 2.3 nm (2.3 x 10–9 m). ●●
What are the building blocks
of the Universe?
What is the material of the Universe made of? Like so many things in
physics, it depends on which model you are using to explain things. Physics
is a series of evermore complex, layered models designed to explain how
the Universe behaves as we see it now. Over the years, as our observations
of the Universe – particularly on the sub-atomic and cosmological scales –
S
E have become more and more detailed, so the physical models have had to
D
LI adapt to the new observations and measurements. It is rare now for a theory
C
U to be developed as the result of a ‘thought’ experiment such as Democritus’.
N
D  Models in physics
N
A
S  In science, and in physics in particular, we rely on models to explain how
E
L the Universe around us works. Models make complex, often invisible
C
I things or processes easier to visualise. Models take many forms. Some,
T
R
like the models of atoms and nuclei used in this chapter, are visual models
A
P
    used as analogies of the real thing. The Rutherford-Bohr model used in the
1 
next section is a good example of this type of model, where the nucleus is
modelled as a small ball containing neutrons and protons, with electrons
2 whizzing round the outside. Atoms don’t actually ‘look’ like this, but it is a
convenient, easy first model to use because it uses the analogy of everyday
objects that we are very familiar with.
Other types of model in physics are more mathematically based. A good
example of this is the kinetic theory of gases, where simple physical rules
expressed mathematically are applied to a model of gas molecules behaving
as hard, bouncy elastic balls. These rules allow the model to predict the
behaviour of real gases.
469884_01_AQA_A-Level_Physics_001-017.indd 2 17/04/19 8:57 AM