IGCSE Physics Workbook

Answers

●● 1 Measurement and motion

Core 8 a 5 × 10–3 m [1]
1 a kilogram [1] b 5 × 10–1 m [1]
b metre [1] c 5 × 103 m [1]
c second [1] d 5 m [1]
2 a 20 [1] e 5 × 10–6 m [1]
b 4 [1] f 5 × 10–9 m [1]
c 120 [1] 9 a 3 [1]
d 500 [1] b 3 [1]
e 1400 [1] c 2 [1]
3 a 15.00 m [1] d 1 [1]
b 1.50 m [1] e 2 [1]
c 0.15 m [1] f 3 [1]
d 0.015 m [1] 10 a 1 m [1]
4 a 1 × 103 [1] b 1.3 m [1]
b 2.25 × 105 [1] c 1.26 m [1]
c 6.5 × 102 [1] 11 yes [1]
d 1.5 × 10 [1]4
12 27 cm2 (do not accept 27.0 cm2) [1]
5 a 10 000 [1]
13 600 cm2 [2]
b 250 [1]
14 75 [2]
c 1 500 000 [1]
d 350 000 000 [1] 15 1.6 s [1]

6 a 1 × 10–3 [1] 16 a 0.16 mm [1]

b 2 × 10–2 [1] b 2 g [1]

c 1.2 × 10–3 [1] 17 3 m/s [2]

d 1.02 × 10–2 [1] 18 a B [1]
7 a i 1 × 10–2 [1] b C [1]
ii 0.01 [1] c 5 m/s [2]
b i 2 × 10–3 [1] 19 a i 270 m [1]
ii 0.002 [1] ii no distance [1]
c i 3 × 10–4 [1] iii 270 m [1]
ii 0.0003 [1] b 1.5 m/s [2]
d i 8 × 10 [1] –4 20 a 4 m/s [2]
ii 0.0008 [1] b friction [1]

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 Answers

21 C [1] Exam focus

22 0.92 g/cm or 920 kg/m [2]
3 3

23 a 40 cm3 [2]
Core
1 a B [3]
b 270 g [1]
b A [3]
24 a 25 cm3 [1]
2 a i increasing [1]
b 8 × 103 kg/m3 [2]
ii constant [1]
25 39 kg [2]
b i constant [1]
Extended ii zero [1]
26 a 0.8 m/s2 [2] c i increasing [1]
b 4 s [2] ii constant [1]
27 12 m/s [2] d OA [1]
28 a 14 m/s [1]
b 840 m [2]
Extended
3 a C [3]
c 0.2 m/s2 [2]
b 0.06 mm [3]
29 a 3.0 m/s [1]
4 a i increasing [1]
b 0.15 m/s2 [1]
ii constant [1]
c 48 m [2]
b i constant [1]
d 21 m [3]
ii zero [1]
30 a i 20 m/s downwards [1]
c i decreasing [1]
ii 20 m [2]
 ii constant [1]
b linear, with slope = 10 m/s2 [2]
d 4.5 km [2]
e AB [1]

●● 2 Forces and momentum

Core 8 a i 25 cm [1]
1 a 13 N [1] ii 10 cm [1]
b 3 N [1] iii 5 cm [1]
2 a 5 N downwards [2] b i 40 cm [1]
b 5 N upwards [2] ii 16 cm [1]

3 force, rest, constant, straight [2] 9 forces, equilibrium, sum, equals, direction,
clockwise, point, moments, no, resultant [5]
4 a 800 N [1]
10 a 3 N [3]
b 800 N [1]
b 3 N [2]
c 500 N [1]
d 800 N [1] 11 Suspend card from one corner and use a plumb
line to draw the vertical line on the card from the
5 a 9000 N [1]
point of suspension; repeat with a different point
b 3600 N [1] of suspension. The centre of gravity is located
6 a 0.15 N [1] where the two lines intersect. [3]
b 0.50 N [1] 12 a u
 ntil the vertical line from its centre of gravity
c 3 N [1] falls outside its base [2]
d 30 N [1] b lower its centre of mass; increase the area of its
7 a 80 kg [1] base [2]

b 128 N [1]

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Extended 23 a 1 kg m/s [2]

b 1 kg m/s [1]
13 0.75 kg [1]
c 500 N [1]
14 D [1]
15 Scalars have magnitude only, e.g. mass; vectors have Exam focus
magnitude and direction, e.g. force. Direction must
be taken into account when adding vectors. [4] Core
1 a [4], b [2]
16 resultant 5 N
4N

extension/mm
4

3 Hooke’s law holds

2 limit of
proportionality
1

0
0 2 4 6 8 10
force/N
3N
c 2 × 103 N/m [2]
5 N [3]
17 a i   20 N to right [2]
Extended
2 a 200 N/m [2]
ii 0.4 m/s2 [2]
b 5 N/m [2]
b i 0 N [1]
c i 20 cm [1]
ii 0 m/s2 [1]
ii 1 N [1]
18 60 N [1]
3 a B [1]
19 a Speed is a scalar and has magnitude only; b i towards the centre of the circle [1]
velocity is a vector and has magnitude and
ii c auses acceleration towards the centre of the
direction. [1]
circle [2]
b Tension in the string acts towards the centre
iii friction between the tyres of the car and the
of the circle, continuously changing the ball’s
road [1]
direction. [1]
iv smaller [1]
c along the tangent to the circle at its lowest
point [1] 4 a 48 N [2]
b 32 N [2]
20 a 15 [1]
5 a 30 000 m/s2 [2]
b 200 [1]
b 30 m/s [2]
21 1 m/s [2]
c follow through longer to extend collision time,
22 a 3 m/s [2] strike harder [2]
b south [1]

●● 3 Energy, work, power and pressure

Core 2 a cannot be used up [1]; two from: solar, wind,
hydroelectric, tidal, geothermal [2]
1 a heat → kinetic energy of turbine [1]
b cannot be replaced once used [1]; two from:
b kinetic energy of rotating turbine → electrical
coal, oil, gas, nuclear [2]
energy [1]

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3 a 10 Pa [1] 16 a i 150 J [2]

b 80 Pa [1] ii 150 J [1]
c 400 Pa [1] iii 10 m/s [3]
d 1.0 × 10  Pa [2]
5
b transferred to heat and sound [2]
4 a 40 N [1] 17 1.8 × 105 W [3]
b 20 N [1]
18 3 × 104 Pa [3]
c 2 × 10  N [2]
–3

d 2 × 10–4 N [2] Exam focus

5 B [2]
Core
6 a 2.5 × 105 Pa [2]
1 a i  renewable, clean [2]
b i 500 N [2]
ii s un does not always shine, expensive to
ii 500 N [1] manufacture [2]
b i high energy density, readily available [2]
Extended
ii r adiation risks, safe disposal of radioactive
7 60 kJ [2] waste required [2]
8 a 1.8 × 105 J [2] c i renewable, clean [2]
b 12 kW [2] ii w
 ind not always available, environmental
9 a 15 J [2] objections [2]
b 2 cm [3] d i high energy density, readily available [2]
10 a 70% [3] ii n
 on-renewable, release carbon dioxide and
b becomes heat [1] sulfur dioxide into atmosphere [2]
 ravitational potential energy → kinetic
11 a g
energy and heat [2]
Extended
2 a 300 N [2]
b electrical energy → electromagnetic energy →
heat [2] b 900 N [2]
c electrical energy → kinetic energy, sound, heat c 300 W [2]
and light [2] 3 a potential energy transferred to kinetic energy
d gravitational potential energy → kinetic and heat (resulting from resistive forces) [3]
energy → electrical energy and heat [2] b 60 J [2]
12 energy, motion, mv2/2, potential, mgh, conserved [3] c i 60 W [1]
13 a 90 [3] ii 8 m/s [2]
b 360 [3] 4 a 27 J [3]
14 a 500 [2] b 0 J [1]
b 1250 [2] c 27 J [1]
d 45 m [2]
15 3 m/s [3]

●● 4 Thermal physics
Core 2 a gas [1]
1 a gas [1] b solid [1]
b solid [1] c liquid [1]
c gas [1] 3 a Fast-moving air molecules collide with the
smoke particles. A smoke particle is much
d liquid [1]
more massive than an air molecule, but when
e solid [1] there are more high-speed molecules striking

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one side of it than the other at a particular 17 Metal transfers heat faster than plastic away from
instant, a net force results and the smoke the hand, because it is a better conductor. [2]
particle will move in the direction of the force.
18 C [1]
The imbalance and the resulting force cause
the smoke particles to change direction rapidly 19 At the bottom; convection can occur if tank heated
in a random manner. [3] at the bottom so more of the water in the tank
b They will move faster. [1] will be heated. [3]

4 Very large numbers of fast-moving molecules 20 D [1]

rebounding from the walls of the container produce 21 D [1]
a force and hence a pressure on the walls. [2] 22 a B [1]
5 a It increases. [1] b C [1]
b The air molecules move faster and so have
23 long-wavelength infrared [1]
more frequent and more violent collisions
with the walls: the average force on the walls 24 thermal, higher, lower, energy, temperature, fluid,
increases. [3] radiation, electromagnetic [4]
6 B, D [2]
Extended
7 B, C [2] 25 a 400 cm3 [1]
8 When the temperature rises the two metals b 100 cm3 [1]
expand by different amounts; this causes the strip 26 a 1 × 105 Pa [1]
to bend and break the contacts to the heating
b 4 × 105 Pa [1]
circuit. On cooling, the strip straightens and
reconnects the heating circuit. [4] 27 a T
 hey vibrate faster and the separation
increases. [2]
9 a 0 °C [1]
b a gas [1]
b 100 °C [1]
10 a t wo from: expansion of a liquid, thermoelectric 28 16 800 [3]
effect, gas pressure, electrical resistance [2] 29 4200 J/(kg °C) [4]
b it should vary continuously [1]; it should vary 30 a B [1]
in a similar way to other physical properties [1] b A [1]
c thermocouple [1]
31 17 000 J [2]
11 a A [1]
32 21 000 J [2]
b 900 J/°C [1]
33 115 000 J [2]
12 Brick and concrete have a high specific heat
capacity and are used to store energy. [2] 34 153 000 J [2]
13 B [1] 35 340 J/g [2]
14 a T
 he temperature at which the substance 36 a 51 000 J [2]
changes from a solid to a liquid. [2] b 170 W [2]
b The temperature at which the substance
37 2300 J/g [2]
changes from a liquid to a vapour. [2]
38 a F
 aster-moving molecules escape from the
15 a C [1]
surface of the liquid. This results in the
b A [1] average speed, and therefore the average
c E [1] kinetic energy of the remaining molecules
d D [1] being lowered, so that the temperature of the
liquid falls. [4]
16 Wrap paper around a metal/wood rod and pass
b two from: large surface area, high temperature,
it through a flame at the junction of the two
draught/vacuum above liquid [2]
materials a few times. The paper chars where it is
wrapped over the wood but not over the metal. c Evaporation can take place at any temperature
Heat is transferred quickly along the metal which and occurs at the surface of the liquid; boiling
is a good conductor. Wood is a poor conductor of only occurs at the boiling point with bubbles
heat and transfers thermal energy very slowly. [4] forming throughout the liquid. [4]

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39 B [1] Switch on the heater for a measured time, t; work

40 a A
 [1]. A black surface is a better emitter of out the energy supplied by heater, P × t. Record
radiation than a shiny one [1]. the temperature of the metal before the heater is
switched on and the highest temperature reached
b i The shiny foil reflects the radiation back into
by the metal just after the heater is switched off;
the room. [1]
work out the temperature rise of the metal, ΔT.
ii The white colour reflects radiation. [1] Measure the mass of the metal, m. Equate energy
supplied by heater to energy gained by metal,
Exam focus P × t = mcΔT. Hence evaluate specific heat
capacity, c. Error in value obtained is due to loss
Core of heat to the environment. [8]
1 a three from: double-glazed windows, cavity
4 a 16 800 J [2]
walls, fur or fleece jackets, string vests,
fibreglass roof insulation [3] b 340m J [2]
b Transfer of heat by convection is restricted. [1] c 63m J [2]
d 403m J [1]
Extended
e water [1]
2 a i  place in pure melting ice [2]
f 42 g [3]
ii p
 lace in the steam above boiling water at
normal atmospheric pressure [2] 5 a Atoms in hot regions pass on their vigorous
vibrations to neighbouring atoms in colder
b 25 °C [1]
regions. Also, in metals, ‘free’ electrons move
c i smaller [1] faster and further in the hot regions and can
ii less [1] transfer that energy to atoms in cooler regions
very quickly. [4]
3 Insert an immersion heater of power P into
the centre of a cylinder of metal and place a b There are no ‘free’ electrons available to move
thermometer into another hole in the cylinder. rapidly through the material, transferring
energy. [1]

●● 5 Properties of waves
Core 6 a no change [1]
b halved [1]
1 Vibrations are perpendicular to direction of travel
for transverse wave, in line with direction of c The direction of travel bends towards normal
travel for longitudinal wave. [4] to boundary. [1]

2  7 lines, direction, ray, beam, diverging, narrower,

faster, before [4]
crest
8 a
displacement

amplitude

distance

trough
wavelength
parallel [1] converging diverging
[4]
b
3 10 Hz [1]
4 1.2 Hz [2]
5 a 6 cm [1]
b 5 Hz [1]
c 30 cm/s [2]
parallel converging [1] diverging

d 32 s [2]

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c 12 a A X

35°

converging diverging [1]

O N

9 B [1]
10 a plane mirror

i r
B C [2]

b i 55° [1]
ii 55° [1]
incident ray normal reflected ray [3] iii 35° [1]
iv 35° [1]
b i 40° [1]
c turned through 180° from incident ray [1]
ii 40° [1]
13 a
11
i ii

i i

normal normal

reflected ray reflected ray 45°

[2]
iii iv
b i 45° [1]
ii 0° [1]
normal i
i normal
14 B, C [2]
15 A real image can be formed on a screen and the
light rays pass through the image. [2]
v vi 16 a I

i normal
normal P Q

a [3]
b [3] O

c [3] [4]

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b virtual [1] iv infrared [1]

c same distance behind mirror as the object is in v X-rays [1]
front [1] vi microwaves [1]
17 a 1 m [1] 31 a radio [1]
b 1 m [1] b X-rays [1]
18 Left and right are interchanged in the image, c X-rays [1]
compared with the object. [2] 32 a M
 icrowaves may harm living cells; use hands-
19 11:01 [2] free devices. [3]

N
b X-rays can kill or damage living cells and cause
20 [2]
cancer; protect by use of lead shielding. [2]

Extended
21 The ray is refracted towards the normal. [2] 33 a 2 × 108 m/s [3]
22 towards, denser, away from, normal, optically, b 2.25 × 108 m/s [3]
normally [3]
34 
23 B [1]
24 a D
 ispersion occurs because the prism has
different refractive indices for different
colours of light. [2]
[2]
b red, orange, yellow, green, blue, indigo,
violet [3]
c  35 a normal
air

red
sunlight
49° 49°
prism
blue

water
[3]
[2]
d blue [1]
e light of one colour (or frequency) [1] b 1.33 [2]
25 When light is incident on a boundary of lesser 36 1.27 [2]
optical density at an angle of incidence greater
37 the one of focal length 5 cm [1]
than a critical angle, c, all of the light is reflected
inside the denser medium. [3] 38 a longitudinal [1]
b transverse [1]
26 thin, two, parallel, focus, undeviated, centre, top,
F, refracted, principal [5] c transverse [1]
d transverse [1]
27 D [1]
e transverse [1]
28 Use the lens to focus an image of a distant object
f longitudinal [1]
onto a piece of paper; the lens–image distance is
equal to the focal length. [2] 39 a 0.4 µm [2]
b 0.7 µm [2]
29 parallel beam [1]
c B [1]
30 a f our from: obey wave equation v = fλ, transverse,
undergo reflection, refraction, diffraction, travel 40 a 1650 Hz [2]
at 3 × 108 m/s in a vacuum [4] b i 20–20 000 Hz [1]
b i infrared [1] ii greater than 20 kHz [1]
ii microwaves or infrared [1] 41 2.64 km [3]
iii X-rays [1]

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Exam focus b 10 cm [1]

c The same [1]
Core 4 a 495 m [3]
1 a b 2 s [3]
5 a 0.99 m [2]
b 6000 m/s [2]
c Use a digital timer to measure the time, t,
that a sharp sound (e.g. a hammer blow
on a metal plate) takes to travel between a
‘start’ and a ‘stop’ microphone. Measure the
distance between the microphones, d. Repeat
[3] measurements of t several times and work out
b an average value. Speed of sound = d/t. [4]

Extended
6 a

[3] 45°

2 a M1

45° 45°

A B
M2 [4]
b i 45° [1]
5° 45° ii periscope [1]
iii can be used to see over higher obstacles [1]
c A, D [2]
7 a

B [5] i
air
b i periscope [1] X
glass
ii binoculars [2] r

3 a

object i
F 2F
2F F C
image
[4]

b Exit ray is parallel to the ray entering the block

but is displaced sideways. [2]
c 19° [4]
[4]

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8 a 10 a i Y [1]
ii X [1]
iii Y [1]
b Molecules in the air vibrate to and fro in
I O C F
the direction of travel of the sound wave;
v when the molecules are moving towards
each other a compression (region of higher
pressure) results; when they are moving
apart a rarefaction (region of lower pressure)
occurs. [3]
b 4 cm [1] [5] c i 0.85 m [1]
c virtual [1] ii 400 Hz [2]
9 a The beam strikes the glass normally. [1] 11 a 28 mm [4]
b 55° [2] b speed = frequency × wavelength [1]
c 42° [3] c 1.4 mm [2]
d 

N P

Q
[2]

●● 6 Electricity and magnetism

Core b

1 pole, south, repel, attract, demagnetised, soft,

steel, permanent [4]
2 a Place a piece of paper on top of the magnet
and sprinkle some iron filings thinly and
evenly onto the paper. Tap the paper gently S N
so that the filings settle into the field lines.
Alternatively use a plotting compass: lay bar
magnet on a piece of paper and place plotting
compass near the N pole. Mark the position of
the N and S poles of the compass on the paper; [3]
then move the compass so that the S pole is at
3 B, D [2]
the point where the N pole was previously and
mark the new position of the N pole. Continue 4 Two from: stroking with another magnet;
until compass is near S pole then join up the hammering in a magnetic field; inserting in a
points to give a field line. Plot other field lines solenoid and increasing d.c. current through the
by repeating the process with the compass at solenoid. [2]
different starting points. [3] 5 a repel [1]

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b repel [1] 15 C [1]

c attract [1] 16 C [1]
6 Electrons are transferred from the Perspex to the 17 a t wo from: LDR, thermistor, microphone,
cloth [1], leaving the Perspex positively charged [1]. pressure switch [2]
7 a + b two from: lamp, LED, loudspeaker, relay,
motor, heater [2]
+
18 a i increases [1]
A ii switches on [1]
iii bell rings [1]
b as a light-operated intruder alarm [1]
[4]
Extended
b +
19 a S
 ome electrons can move easily from atom to
atom [1] and can be considered to be ‘free‘
+ electrons [1].
A b All electrons are firmly bound to atoms [1] and
there are no ‘free’ electrons available to
produce a current [1].
20 D [1]
21 a 
+ + + + +
[4]

8 In a.c. the direction in which current flows

reverses regularly; in d.c. the current flows in
one direction only. [4]
9 a It is dimmer. [1]
– – – – –
b It has the same (full) brightness. [1]
[3]
c It is dimmer. [1]
10 a potential difference = current × resistance [2] b
b Connect a battery, ammeter, variable
resistor and the wire whose resistance
is to be measured, in series. Connect
a voltmeter across the wire. Measure
V and I with different settings of the +
variable resistor. Evaluate R = V/I for
each setting. [4]
11 1.2 V [1]
12 6 Ω [2]
[3]
13 0.3 A [2]
14 a 15 Ω [2] 22 a 20 C [2]
b 0.1 A [2] b 600 C [2]
c 0.6 V [2] 23 a 2 A [2]
d 0.9 V [2] b 1 A [2]

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24 C [1] 34 B [1]
25 a B [1] 35 I
b i 2.5 V [2]
ii 7.5 V [2]
26 a 3 J [2]
b 360 J [3]
27 a 4 C [2]
b 0.4 A [2]
28 a Connect four cells in series. [2]
b 12 J [2]
0 V [3]
29 a coulomb C [1]
b ampere A [1] 36 a 2.4 kW [2]
c volt V [1] b 5760 kJ or 1.6 kWh [2]
d volt V [1] 37 a 14 400 kJ [2]
e ohm Ω [1] b 8 A [2]
30 a 3 Ω [4] 38 a 200 J/s [2]
b 2 A [2] b 60 kJ [2]
c 1.5 A [2] 39 3 A [2]
d 0.5 A [2] 40 C [3]
31 a I
41 It only allows current to flow in one direction, so
converts a.c. to d.c. [3]
42 Analogue voltages vary continuously [1]; digital
voltages have discrete values,
for example, high or low [1].
43 a analogue [1]
b digital [1]
c digital [1]
d analogue [1]
0 V [3]
44 a NOT gate
b I
input output
[1]
b It gives a high output if input low, and vice
versa. [2]

45 a  OR gate
A input
output
0 V [3]
B input [1]
32 a It is constant. [1]
b It increases as lamp heats up. [1] b  NOR gate
33 a doubled [1] A input
b halved [1] output

c doubled [1] B input [1]

d halved [1]

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c  AND gate d It ensures the current-carrying capacity of the

A input wiring is not exceeded. (It melts and breaks
the circuit if the current becomes greater than
output
the fuse rating.) [2]
B input [1]
Extended
2 a All at same brightness because they have the
d  NAND gate
same voltage across them; if one lamp fails, the
A input
rest remain lit. [2]
output
b i 0.3 A [2]
B input [1]
ii 6 A [2]
46 a low [1] iii 5.7 A [2]
b high [1] 3 a i 0.3 A [2]
47 AND [2] ii 5.4 V [2]
iii 3.6 V [2]
Exam focus b i 0.2 A [2]
Core ii 6.6 V [2]
1 a no damaged insulation, exposed wires, loose iii 2.4 V [2]
connections or short circuits [1]; plug correctly c increases [1]
wired [1]
4 a i increases [1]
b Water lowers the resistance of the path to earth
ii increases [1]
so the current increases. [2]
iii decreases [1]
c The current through wire is too high. [2]
b 14 Ω [4]

●● 7 Electromagnetic effects
Core 7 a downwards [1]
b i upwards [1]
1 B [1]
ii upwards [1]
2 a.c. voltages can be stepped up and down easily
using transformers. Extended
3 C [1] 8 a does not move [1]
4 a 12 V [3] b swings to right [1]
b step-down [1] c swings further to left [2]
5 larger current [1], more turns on solenoid [1] d swings to right [2]

6 9 current flows to the right [2]

10 a N [1]
b S [1]
field lines
c N [1]
11 B [1]
12 a 0.2 A [2]
b 0.6 J/s [2]
13 dropping, hammering or heating in the absence
current
direction of a magnetic field [1]; inserting in a solenoid and
[3]
decreasing a.c current through the solenoid [1]

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14 a i B [1] b yes [1]

ii reverse current direction [1] c 0.75 A [1]
iii left [1] d 50 N [1]
b i inside solenoid [1] e Q could lift a heavier load with a given
ii outside solenoid [1] current. [1]
15 a 3.0 A [3]
Extended
b 2.7 A [2]
3 a They maintain contact with the brushes as the
16 B [1] coil rotates. [1]
17 travel at high speed in straight lines in a vacuum b
[1]; cause emission of light when they strike a
fluorescent screen [1]; deflected by an electric field
[1]; deflected by a magnetic field [1]

voltage
time
18 upwards (towards the positive plate) [1]
19 upwards [1]

Exam focus [3]

Core c horizontal [1]
1 a The current through the coil reaching the d a.c. [1]
‘pull-on’ value. [1]
4 a It causes the coil to turn. [1]
b It becomes magnetised by current in coil and
b increase current in coil [1]; increase number
attracts the iron armature. [2]
of turns on coil [1]; increase strength of
c Contact is made in circuit PQ. [2] magnet [1]
d It is used to control power in a second circuit; c The coil would turn faster. [1]
especially useful if second circuit requires a
d It causes a change of direction of the current in
larger current. [2]
the coil every half-turn  [1] so that the direction
2 a  of the couple on the coil stays constant [1].
100

5 a 400 [3]
b 200 W [2]
80
c 0.2 A [3]
d It reduces the efficiency. [1]
60
load/N

40

20

0
0 0.5 1.0 1.5 2.0 2.5
current/A
[4]

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●● 8 Atomic physics
Core 11 nuclides that have the same proton number (Z)
but different nucleon numbers (A) [3]
1 a α-particles [1]
12 a 14 [1]
b γ-rays [1]
b i 6 [1]
c γ-rays [1]
ii 6 [1]
d α-particles [1]
iii 6 [1]
e β-particles [1]
c yes [1]
f α-particles [1]
2 a β-particles [1] Extended
b α-particles [1]
13 downwards [1]
c γ-rays [1]
14 a i decreases [1]
d β-particles [1]
ii increases [1]
e γ-rays [1]
b β   [1]; the radiation will pass easily through
f α-particles [1] the paper and be readily detected by a Geiger
g β-particles [1] counter [1]
3 a Electrons are removed from atoms/molecules 15 Most of the incident α-particles pass straight
[1]; leaving behind positive ions [1]. through, while some are deflected through an
b by a Geiger counter/GM tube or a charged appreciable angle and a few bounce back. [3]
electroscope [1] 16 a i 131 [1]
4 B [1] ii 54 [1]
5 a time for activity of a radioactive sample to b 78 [1]
halve/average time for half the nuclei in a c decreases to 77 [2]
sample to decay [3]
b radiation from environment: cosmic rays, Exam focus
radioactive sources in the air and rocks
around us [3] Core
6 one half-life: 5700 years [2] 1 a two from: damage living cells and tissues
leading to cancer, eye cataracts, radiation
7 40 minutes [1] burns/sickness, death; cause gene mutation [2]
8 G [1] b two from: radioactive tracers in medicine
or agriculture, thickness testing and flaw
9 a +1 [1]
detection in industry, dating of materials,
b 0 [1] sterilisation, radiotherapy, smoke detectors [2]
c +2 [1] c two from: use lead or concrete shielding,
d −1 [1] handle sources with long forceps, keep away
e 0 [1] from the eyes, keep in lead boxes [2]
f +2 [1]
Extended
10 a A = Z + N [1]
b Z [1] 2 a 
the break-up of a large nucleus into two
smaller nuclei of nearly equal size [2]
c i 42 He [1]
b i 144 [2]
ii −10 e [1]
ii 36 [2]
iii 10 n [1]

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c i k.e. of emitted particles [1] d electromagnetic radiation [1]

ii heats water to produce steam, which then 4 a i 4 [2]
drives a generator [1] ii 2 [2]
3 a the union of two light nuclei [1] into one b α-particle [1]
heavier nucleus [1]
c causes ionisation of the air [1]
b i 4 [2]
ii 1 [2]
c i He [1]
ii H [1]

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