Chapter 1 Motion - Hodder Plus Home

GCSE Physics for CCEA second edition
Chapter 1 Motion
In-text questions
1. a) average speed = total distance ÷ total time
= 800 ÷ 40s
= 20m/s
b) Car may be overtaking or braking.
2. a) distance = speed x time
= 10m/s x 9s
= 90m
b) time = distance/speed
= 220m ÷ 10 m/s
= 22s
3. a) Displacement is distance in a given direction i.e., it is a vector quantity.
b) Velocity is speed in a given direction i.e., it is a vector quantity.
4. a) Runner: average speed = 400m ÷ 44s
= 9.09 m/s
b) Car: average speed = 175 miles ÷ 3 hour
= 5 miles per hour
c) Shuttle: average speed = 43 750 000m ÷ 2.5 x 60 x 60s
= 4860 m/s
5. a) An acceleration of 3m/s2 means that the train’s velocity increases by 3m/s in each and every
subsequent second.
b) The velocity of the bus decreases by 2m/s in each and every subsequent second.
6. acceleration = change in velocity/time
= (30 – 3) m/s ÷ 8s
= 27 ÷ 8
= 3.375 m/s2
7. u = 25 m/s, v = 0 m/s (comes to a halt), t = 5 s, a = ?
0 - 25
- 25
v-u
= -5m/s2 or deceleration = 5m/s2


a
t
5
5
8. a) u = 0 m/s, v = ?, t = 5 s, a = 4 m/s2
v-u
v-0
a
4
v = 20m/s
t
5
b) u = 28 m/s, v = ?, t = 8 s, a = 4 m/s2
v = u + at
= 28 + (4 x 8)
= 28 + 32
= 60 m/s
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GCSE Physics for CCEA second edition
9.
10. a) & b)
c) i) Paul
ii) Paul takes 3.5s, Jim takes 5.5s.
iii) 3m.
iv) No, gradient changes after 6s.
v) Average speed = 14m ÷ 7s = 2m/s.
11. Speed increases then becomes steady. Speed is not zero at time t = 0s.
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GCSE Physics for CCEA second edition
12. a) Acceleration = gradient
= 25 ÷ 5
= 5 m/s2
b) total displacement = area of triangle + area of rectangle
= (125 ÷ 2 ) + (25 x 10)
= 312.5m
13. a) i) OA = Uniform acceleration
ii) AB = Constant velocity
iii) BC = Uniform deceleration
b) i) Acceleration = gradient = 5m/s ÷ 2s = 2.5m/s2
ii) total distance = area of triangle + area of rectangle + area of triangle
= 5m + 5m + 10m
= 20m
iii) average speed = total distance travelled ÷ time taken
= 20m ÷ 7s
= 2.86m/s
14. u = 20m/s, v = ?, t = 10s, a = 3 m/s2
v = u + at
= 20 + (3 x 10)
= 20 + 30
= 50 m/s
15. u = 0m/s, a = 0.3m/s2, t = 10s, s = ?
v = u + at
= 0 + 10 x 0.3
= 3m/s
s = ut + ½ at2
= 0 + ½ x 0.3 x 102
= 0.3 x 50
= 15m
16. u = 20m/s, v = 0, a = -10m/s2, t = ?, s = ?
v = u + at
0 = 20 – (10 x t)
10t = 20
t = 25 s
s = ut + ½ at2
= (20 x 2) – (½ x 10 x 22)
= 40 - 20
= 20m
17. u = 0m/s, v = ?, a = 10 m/s2, t = 3s, s = ?
a) v = u + at
v = 0 + 10 x 3
v = 30m/s
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GCSE Physics for CCEA second edition
b) average speed = (30 + 0) ÷ 2
= 15m/s
c) s = ut + ½ at2
= 0 + ½ x 10 x 32
= 45 m
18. s = 500m, u = 0m/s, v = ?, a = 10 m/s2, t = ?
a) v2 = u2 + 2as
= 2 x 10 x 500
= 10 000
v = 100m/s
b)
v
100
10t
t
= u + at
= 0 + 10t
= 100
= 10s
19. u = 50m/s, v= 0, a = -10m/s2, t = ?, s = ?
a) v = u + at
0 = 50 – (10 x t)
10t = 50
t = 5s
b) s = ut + ½ at2
= (50 x 5)-(½x10x25)
= 250 – 125
= 125m
20. a) u = 0 m/s, v = ?, a = 3 m/s2, t = 5s
v = u + at
=0+3x5
= 15m/s
b) u = 15, v = 0, t = ?, a = -0.5
v = u + at
0 = 15 – (0.5 x t)
0.5t = 15
t = 30s
area of triangle = ½ x b x h
= ½ x 35 x 15
= 262.5m
c)
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GCSE Physics for CCEA second edition
Exam questions (pages 11–12)
1. a) distance = 3km = 3000m, time = 5 mins = 300s, average speed = ?
total distance
3000m
=
= 10m/s
average speed 
total time
300 s
b) i) acceleration = gradient = 14m/s ÷ 20s = 0.85 m/s2
(6 marks)
(5 marks)
ii) RF = m x a = 1500kg x 0.85m/s = 1275N
RF = driving force – drag
drag = 3000 – 1275 = 1725N
(7 marks)
iii) Distance travelled from 80s to 200s is the area of the trapezium:
= ½ (a + b) x h
= ½ (120 + 80) x 20
= 100 x 20
= 2000m
(6 marks)
c) i) Constant velocity
ii) Deceleration
iii) Stationary
(3 marks)
d) mass = 1500kg, velocity = 14m/s, momentum = ?
momentum = mass x velocity
= 1500kg x 14m/s
= 21 000kgm/s
(5 marks)
2
2. a) mass = 10 000kg, g = 10m/s , weight = ?
weight = mass x g
= 10 000kg x 10m/s2
= 100 000N
b) 100 000N
c) area = 20m x 5m = 100m2, upward force = 100 000N, pressure =?
force 100 000 N
pressure 

= 1000 Pa
area
100 m 2
d) Arrow to the right.
e) RF = 20000 – 15000 = 5000N, mass = 10000kg, acceleration = ?
RF = m x a
5000 = 10000 x a
5000
a
= 0.5 m/s2
10 000
3. a) The graph does not go below time axis.
(2 marks)
(1 mark)
(4 marks)
(1 mark)
(4 marks)
(1 mark)
b) acceleration = gradient = 10m/s ÷ 50s = 0.2m/s2
(3 marks)
c) t = 100s
(1 mark)
d) i) Stage BC = area of rectangle = 50 x 10 = 500m
(2 marks)
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GCSE Physics for CCEA second edition
ii) Stage CD = area of triangle = ½ x b x h = ½ 125 x 10 = 625 m
e) average speed 
total distance
250  500  625
=
= 6.11 m/s
total time
225
f) work done = force x distance = 5000N x 500m = 2500 000J
4. a) i) speed = gradient = 14m ÷ 7s = 2m/s
ii)
b) i) potential energy = mass x g x height
320 000J = 80 kg x 10 m/s2 x height
height = 320 000 ÷ 800 = 400m
ii) kinetic energy = ½ x m x v2
= ½ x 80 x 142
= 7840J
(3 marks)
(3 marks)
(3 marks)
(2 marks)
(2 marks)
(3 marks)
(3 marks)
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GCSE Physics for CCEA second edition
Chapter 2 Forces
In-text questions
1. a) No acceleration means balanced forces, so there must be a backwards force of 40N acting on
bicycle and rider; friction and air resistance.
b) RF = 70 – 40 = 30N, m = 90kg, a = ?
RF = m x a
30 = 90 x a
a = 30 ÷ 90 = 0.33m/s2
2. m = 1200 kg, a = 2 m/s2, RF = (3000 – frictional force)
RF = m x a
3000 – frictional force = 1200 x 2
3000 – frictional force = 2400
3000 – 2400 = frictional force
600 = frictional force
or frictional force = 600N
3. a) Forwards.
b) Consider horizontal forces only. RF = (2000 – 400) = 1600N, m = 800kg, a = ?
RF = m x a
1600 = 800 x a
a = 1600 ÷ 800 = 2m/s2
4. a) weight = mass x acceleration due to gravity
= 2000 kg x 10 m/s2
= 20000N
b) Consider vertical forces. RF = (25000 – 20000) = 5000N, m = 2000kg, a = ?
RF = m x a
5000 = 2000 x a
a = 5000 ÷ 2000 = 2.5m/s2
5. 300N forward thrust. Frictional force due to water must also be 300N backwards, if it travels at
constant speed. RF = (? - 300), m = 500kg, a = 2 m/s2
RF = m x a
(? -300) = 500 x 2
(? -300) = 1000
? = 1000 + 300
= 1300N
6. RF = (? - 400) N, m = 1200kg, a = 3m/s2
RF = m x a
(? -400) = 1200 x 3
(? -400) = 3600
? = 3600 + 400
= 4000N
7. a) u = 24m/s, v = 0m/s (brings to rest), t = 8s, a = ?
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GCSE Physics for CCEA second edition
a
v-u
0 - 24  24


= -3m/s2 or deceleration = 3m/s
8
8
t
b) RF = ?, a = 3 m/s, m = 1200 kg
RF = m x a
= 1200 x 3
= 3600N
NB: No need to substitute a = -3 m/s into formula, as we are only asked for the size of the
unbalanced force!
8. a) Forces acting on girl must be balanced i.e., the backwards frictional force must also be 120N
if the girl is travelling at a steady speed.
b) RF = 300 – 120 = 180N, m = 60kg, a = ?
RF = m x a
180 = 60 x a
a = 180 ÷ 60 = 3m/s2
9. a) u = 50m/s, v = 0m/s, t = 5s, a = ?
v-u
0 - 50
a

= -10m/s2
5
t
b) a = 10 m/s2, m = ?, RF = 18000N
RF = m x a
18000 = m x 10
m = 18000 ÷ 10 = 1800kg
10. a) u = 20m/s, v = 0m/s, t = 0.1s, a = ?
v-u
0 - 20
a

= -200m/s2 or deceleration = 200m/s2
0.1
t
b) F = ?, m = 1000kg, a = 200m/s2
F=mxa
= 1000 x 200
= 200000N
11. a) 30km/hr = 30000m in 3600 seconds = 8.33m/s
b) u = 8.33m/s, v = 0m/s, t = 0.03s, a = ?
v-u
0 - 8.33
a

= -277.7m/s2
0.03
t
c) a = 277.7m/s2, m = 70kg, RF = ?
RF = m x a
= 70 x 277.7
= 19 444 N
12. Weight is measured in Newtons, so Julie should have said ‘My weight is 350 N’ or ‘My mass is
35 kg’.
13. As soon as it enters the oil, the ball will decelerate until its weight is equal to the viscous drag.
Then the ball will fall with constant (terminal) velocity.
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GCSE Physics for CCEA second edition
14. There is no atmosphere on the Moon. The hammer and feather will experience no drag forces, so
they will both accelerate at 1.6 m/s2 and hit the surface of the moon simultaneously.
15. When the parachute opens, the vertical drag force increases, decreasing the velocity of the
parachutist.
16. AB – Parachutist is decelerating, the faster he falls the greater the air resistance he experiences
until at
BC – air resistance equals weight, balanced forces, so that parachutist falls at constant (terminal)
velocity of roughly 60 m/s.
CD – at C the parachute opens whereupon the air resistance increases, deceleration occurs, until
at
DE – the parachutist reaches a smaller and safer terminal velocity.
17. volume = 3 m3, mass = 57.9 g, density = ?
mass
57.9
density 

= 19.3 g/cm3
volume
3
Consulting table: substance = gold
18. a) volume = 20 cm3, mass = ?, density = 2.7 g/cm3
mass = density x volume
= 2.7 x 20
= 54 g
b) volume = ?, mass = 54 g, density = 2.7 g/cm3
mass
54
volume 

= 20 cm3
density
2.7
19. volume = 15 cm3, mass = 120 g, density = ?
mass
120
volume 

= 8 cm3
density
15
20. volume = 10 m x 5 m x 3 m = 150 m3, mass = ?, density = 1.26 kg/m3
mass = density x volume
= 1.26 x 150
= 189 g
21. volume = (35 -15) = 20 cm3, mass = 60 g, density = ?
mass
60
density 

= 3 g/cm3
volume
20
22. volume = 0.8 m3, mass = ?, density = 800 kg/m3
mass = density x volume
= 800 x 0.08
= 64 g
23. volume of air = 100 cm3, mass of air = (351.2 – 350) = 1.2 g, density = ?
mass
1.2

= 0.012 g/cm3
density 
volume
100
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GCSE Physics for CCEA second edition
24. a) volume of rivets = 70 – 50 = 20 cm3
b) volume of 1 rivet = 20/100 = 0.2 cm3
c) volume of air = 20 cm3, mass of air = 180 g, density = ?
mass
180
density 

= 9 g/cm3
volume
20
25. a) clockwise moment = force x perpendicular distance to pivot
= 150 x 0.9
= 135 Nm
b) clockwise moment = anticlockwise moment
135 = F x 1.35
135
= 100 N
F
1.35
26. clockwise moment = anticlockwise moment
3 x X = 4 x 36
4 x 36
X =
= 48 cm
3
27. a) moment exerted by boy = force x perpendicular distance to pivot
= 100 N x 4 m
= 400 Nm
b) If in equilibrium: moment exerted by man = moment exerted by boy
= 400 Nm
c) moment exerted by man = force x distance to pivot
400 = force x (4 – 3)
= force x 1
force = 400 N
28. a) clockwise moment of 5 N force = 5N x 40 cm
= 200 Ncm
b) anticlockwise moment = clockwise moment
weight x 25 cm = 200 Ncm
200
weight 
25
= 8N
29. clockwise moment = anticlockwise moment
F x 225 = 600 x 75
600 x 75
F
225
= 200 N
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GCSE Physics for CCEA second edition
30. clockwise moment = anticlockwise moment
F x 0.6 = 100 x 0.3
100 x 0.3
=
0.6
= 50 N
31. a) Where medians of triangle meet, middle of rectangle.
b) In the centre of the cut-out circle, ie., not in the plastic sheet itself.
32. a) It is a point through which the whole weight of the object appears to act.
b) i) The centre of gravity of the pencil and the penknife is on a line below the point of the
pencil.
ii) The penknife and pencil would topple.
33. a)
b) Low centre of gravity and wide wheel base.
34. a)
b) The whiskey glass.
c) Lower centre of gravity and wider base.
35. a)
i) unstable
ii) neutral
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GCSE Physics for CCEA second edition
b) i)
ii) B.
iii) Lower centre of gravity and wider base.
36. a)
X
Y
Z
centre of gravity
outside lamina
b)
Exam questions (page 35)
1. a) Density is the ratio of the mass to volume.
b) See Figure 12a page 23.
(2 marks)
(4 marks)
3
c) Volume = 2.4 cm , mass = 46g, density = ?
mass
46
density 

= 19.2g/cm3
volume 2.4
d) Gold.
2. a) i)
volume = l x b x d
= 1.8 x 1.2 x 0.1
= 0.216 m3
(3 marks)
(1 mark)
(4 marks)
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GCSE Physics for CCEA second edition
mass
520

= 2407.4kg/m3
volume 0.216
This density is greater than 2350 kg/m, therefore this slab will be suitable.
NB: mass of slab = 520kg, not 520g as in question.
ii) density 
(4 marks)
b) i) The centre of gravity is a point through which the whole weight of the body appears to
(1 mark)
act.
ii) moment = force x perpendicular distance to pivot
= 1500N x 0.4m
= 600Nm
iii) anticlockwise moment = clockwise moment
effort x (0.4 + 0.7) = 600
effort x 1.1 = 600
600
= 545N
effort 
1.1
iv)
upward forces = downward forces
reaction + 545N = 1500N
reaction = 1500 – 545
= 955N
(5 marks)
(4 marks)
(2 marks)
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GCSE Physics for CCEA second edition
Chapter 3 Energy
In-text questions
1. Any three from: coal, oil, (natural) gas, lignite, peat (turf).
2. Sound, electricity and heat are energy forms. The others are not forms of energy.
3. Hydroelectricity, wind and tides are renewable. Gas, oil and coal are non-renewable.
4. The solar cells change light energy into electrical energy. The battery stores chemical energy.
As the propellers turn they change electrical energy into useful kinetic energy. As the model
aircraft gains height, it gains gravitational potential energy. The model aircraft crashes into the
ground. As it does so, it produces wasted heat and sound energy.
5. Renewable resources are in limitless supply because they are replaced by nature in less than a
human lifetime.
6. ▪


Both use water to produce steam which drives a turbine.
A nuclear power station uses fission of uranium to produce heat and the waste products are
dangerously radioactive.
A fossil fuel power station burns fossil fuels to produce heat. One of the waste products,
carbon dioxide, is a major contributor to global warming.
7. The waste will be dangerously radioactive for a very long time and there can be no guarantee that
it will not leak. There is also the possibility of seismic activity (earthquakes) bringing it to the
surface.
8. Carbon dioxide.
9. Prevailing winds blow sulphur dioxide from Britain to Norway.
10. See table and text on pages 39–40.
11. See table and text on pages 39–40.
12. Open-cast mining for lignite would ruin the beauty of a naturally very attractive area.
13. See text on pages 37 and 40.
14. Conserve fossil fuels, wind is renewable, less atmospheric pollution leading to global warming.
15. The materials used to generate electricity (fossil fuels and uranium) themselves produce very
polluting waste products.
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GCSE Physics for CCEA second edition
16.
Device/situation
Input energy form
Microphone
Electric smoothing iron
Loudspeaker
Coal burning in an open fire
A weight falling towards the
ground
A candle flame
sound energy
electrical energy
electrical energy
chemical energy
gravitational
potential energy
chemical energy
Battery-powered electric drill chemical energy →
→
→
→
→
→
→
electrical
energy →
Useful output
energy form
electrical energy
heat energy
sound energy
heat energy
kinetic energy
heat energy and
light energy
kinetic energy
17. work (in J) = Force (in N) x distance (in m) = (100 x 10)N x 5.5m = 5500J
18. work (in J) = Force (in N) x distance (in m) = 60N x 20m = 1200J
19. a) efficiency 
useful energy output
750

= 0.75
total energy input
1000
b) Heat is lost to the metal of the boiler, to the surroundings and in the hot smoke through the
chimney. Sound is lost to the environment.
useful energy output
total energy input
Since, by the Law of Conservation of Energy, energy is neither created nor destroyed, the useful
energy output can never be greater than the total energy input.
20. efficiency 
useful energy output
total energy input
140 000
0.28 
total energy input
140 000
total (chemical) energy input 
= 500 000kJ
0.28
21. efficiency 
22. energy (in J) = power (in W) x time (in s) = 3600W x (5 x 60)s
= 1 080 000 J
23. a) weight = mg = 1500kg x 10N/kg = 15 000N
b) work = force x distance = 15 000N x 12m = 180 000J
c) time (in s) 
work (in J)
180000

= 60s
power (in W)
3000
d) speed (in m/s) 
distance (in m) 12

= 0.2m/s
time (in s)
60
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GCSE Physics for CCEA second edition
24. a) work (in J) = force (in N) x distance (in m) = 1000N x 0.4m = 400J
b) efficiency 
useful energy output
400

= 0.33
total energy input
1200
25. KE = ½ mv2 = ½ x 120 x 30002 = 540 000 000 J
26. GPE of rubber = mgh = 0.050 kg x 10 N/kg x 280 m = 140 J
KE of shell = ½ mv2 = 0.5 x 0.010 x 1502 = 112.5 J
Comment: if energy losses are ignored, KE of shell is less than that of rubber as it hits the
ground.
27. KE of tanker = ½ mv2
200 000 000 = 0.5 x 100 000 000 x v2
v2 = 4
v = 2 m/s
28.
Height above
ground in m
5.0
4.0
3.2
1.8
0.0
Gravitational
potential
energy in J
100
80
64
36
0
Kinetic energy
in J
Total
energy in J
Speed in m/s
0
20
36
64
100
100
100
100
100
100
0
4.47
6.0
8.0
10.0
29. KE of car = ½ mv2
160 000 = 0.5 x 800 x v2
v2 = 400
v = 20 m/s = (20 x 60) metres/min = 1.2 km/min = 1.2 x 60 km/hr = 72 km/hr
30. GPE = mass x gravitational field strength x height
176 = 2 x g x 10
g = 176 ÷ 20 = 8.8 N/kg
By inspection of the table, the planet was Venus.
31. a) KE (in J) as ball rises from ground = GPE of ball at its maximum height
10 J = 0.2 kg x 10 N/kg x height in metres
Height = 10 ÷ 2 = 5 metres
b) In practice, energy is lost as heat and sound against air resistance as the ball rises. So, not all
of the KE of the ball is converted into GPE.
32. a) efficiency 
useful energy output
(25  20)

= 0.2
total energy input
25
b) The principle of Conservation of Energy.
33. a) useful energy output = efficiency x total energy input = 0.3 x 2000 = 600 J
b) total wasted energy = 2000 – 600 = 1400 J
wasted heat energy = 0.9 x total wasted energy = 0.9 x 1400 = 1260 J
percentage of the input energy lost as heat = (1260 ÷ 2000) x 100% = 63%
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GCSE Physics for CCEA second edition
Exam questions (pages 55–57)
1. a) Kinetic energy and gravitational potential energy.
b) i) Input kinetic energy of wind → Useful output electrical energy
(2 marks)
(2 marks)
ii) Wind energy is in almost limitless supply because it is replaced so quickly by nature.
(1 mark)
iii) Other renewables are wave energy and solar energy.
c) Gravitational potential energy → Kinetic energy → Electrical output energy
stored in upper lake
in moving water from the power station
(2 marks)
(3 marks)
2. Advantage: tidal energy has low running costs (but huge set-up costs).
Disadvantage: while the tides (unlike wind and waves) are predictable, they vary from day to day
and month to month. This makes them unsuitable for producing a constant daily amount of
(2 marks)
electrical energy.
3. a) i) Oil is a non-renewable fuel because it is not being replaced by nature.
(2 marks)
ii) Wind energy is renewable because it is in almost limitless supply because it is replaced
(2 marks)
so quickly by nature.
iii) Non-renewable resources, such as coal, oil and gas are generally more reliable than
(1 mark)
renewable energy sources like wind, waves and solar energy.
b) i) GPE lost per second = mgh = 100 000 000 x 10 x 50 = 50 000 000 000 J/s or 5 x 1010 J/s
(3 marks)
ii) Maximum power output = (0.8 / 100) x 50 000 000 000 = 400 000 000 W
(3 marks)
iii) The water flowing over the falls comes from rainfall. Rainfall occurs as part of the water
cycle in which water in the oceans is evaporated by the sun, rises and condenses to form
clouds. The clouds are driven by the wind over land and the water falls as precipitation to
(2 marks)
form rivers and lakes. Some of this water passes over the falls.
c) i) useful power output = efficiency x electrical power input = 0.6 x 500 = 300 W
(3 marks)
ii) 300 J
(1 mark)
iii) power = force in rope x distance moved per second
300 = 1200 x distance moved per second
constant speed of vehicle = distance moved per second = 300 ÷ 1200 = 0.25 m/s
(3 marks)
4. a) work = force x distance = 8000N x 1.8m = 14 400J
b) time 
26000
work

= 5s
power
5200
c) power input 
5200
useful power output

= 20 000 W = 20 kW
efficiency
0.26
(3 marks)
(3 marks)
(3 marks)
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GCSE Physics for CCEA second edition
5. work = force x distance = 550N x 3m = 1650J
(3 marks)
6. a) work = force x distance = 24 000N x 40m = 960 000J = 960kJ
(3 marks)
b) power 
work
960

= 48kW
time
20
c) efficiency 
(3 marks)
useful energy output
960

= 0.8
total energy input
1200
(3 marks)
d)
Energy
Potential energy of the top
tramcar
Kinetic energy of the top
tramcar
Kinetic energy of the bottom
tramcar
Potential energy of the
bottom tramcar
Heat energy
Increases/decreases/
unchanged
DECREASES
UNCHANGED
UNCHANGED
INCREASES
INCREASES
(5 marks)
7.
Quantity
Speed of ball
Potential energy of ball
Total energy of ball
Kinetic energy of ball
Increases
Decreases
✓
Constant
✓
✓
✓
(4 marks)
8. a) Grade A dishwasher costs less to run than D.
(1 mark)
b) Electrical energy is converted into USEFUL HEAT energy and USEFUL KINETIC energy
(4 marks)
and WASTED SOUND energy.
c) A shopper might not always buy the most efficient appliance which a shop has for sale
(2 marks)
because the most efficient appliance might be the most expensive.
18
GCSE Physics for CCEA second edition
Chapter 4 Radioactivity
In-text questions
1. 1. 6 protons, 8 neutrons, 0 electrons (electrons are not in the nucleus).
2.
23
11
Na
3. The nuclei of isotopes have the same atomic number (same number of protons), but they have a
different mass number (a different number of protons + neutrons).
4. a) β decay (no change in mass number, but change in name of nucleus)
b) α decay (reduction in mass number of 4)
c) α decay (reduction in mass number of 4)
5. a) 210
b) 212
c) 210
6. a) Decreases by 4
b) Decreases by 2
c) Unchanged
d) Increases by 1
Exam questions (pages 72–3)
1. a)
Particle
Electron
Neutron
Proton
Mass
1/1840
1
1
Charge
–1
0
+1
Number
6
6
6
Location
Orbiting nucleus
In the nucleus
In the nucleus
(7 marks)
b) i) A nucleus is radioactive if it decays by emitting α particles, β particles or γ radiation.
(2 marks)
ii) Radon is radioactive and it emits radiation which can cause serious damage to lung
tissues. The decay products might also lodge permanently in the lungs. These decay
products are also radioactive and will go on causing damage to tissues. This damage may
lead to cancers.
(2 marks)
ii) Nuclei with the same number of protons but a different number of neutrons are called
isotopes.
(2 marks)
c) i) Points plotted at: (0, 800), (20, 400), (40, 200), (60, 100), (80, 50)
ii) Curve passing through these points.
(5 marks)
(1 mark)
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GCSE Physics for CCEA second edition
d) i) A beam of beta particles will all be absorbed by a sheet of aluminium several mm thick
(1 mark)
placed in their path.
ii)
(3 marks)
iii) First measure the background count rate. Then measure the count rate for increasing
thicknesses of aluminium.
(3 marks)
iv) Increase the thickness of the aluminium between the source and the Geiger tube and
measure the corresponding count rate until the count rate is equal to the background
count. Then measure the thickness of the aluminium – this thickness is the range of beta
particles in aluminium.
(2 marks)
v)
2. a)
14
6
C  147 N  -01 β
(2 marks)
(4 marks)
b) Firstly, alpha radiation is so ionisng that it is likely to cause serious harm to tissues within the
body. Secondly, alpha radiation has such a small range that it cannot leave the body and be
detected by the camera.
(2 marks)
c) i) Background activity comes from rocks containing uranium and other radioactive
elements, the waste products from nuclear power stations and Nuclear Medicine
Departments in hospitals and cosmic rays from space. To obtain the corrected count rate
the experimentalist subtracts the background count rate from the measured count rate.
Corrected count rate = Observed count rate less Background count rate.
(2 marks)
20
GCSE Physics for CCEA second edition
ii)
(5 marks)
iii) Half life = time taken for activity to fall from original value to half of original value.
(2 marks)
From graph, the half life is 29 seconds.
3. a) i) In alpha decay the mass number decreases by 4 and the atomic number decreases by 2.
(2 marks)
ii) In beta alpha decay the mass number remains the same and the atomic number increases
by 1.
(2 marks)
b)
Element
(symbol)
U
Th
Pa
U
Th
Ra
Rn
Po
Pb
Bi
Atomic
number
92
90
91
92
90
88
86
84
82
83
Mass
number
238
234
234
234
230
226
222
218
214
214
Decays
by emitting










Leaving
element
Th
Pa
U
Th
Ra
Rn
Po
Pb
Bi
Po
(3 marks)
c) Student’s graph.
(5 marks)
d) Gamma emission gives no change to atomic number and mass number.
(1 mark)
e)
238
92
U and
234
92
U are isotopes;
234
90
Th and
230
90
Th are isotopes.
(2 marks)
4. a) i) The half-life of an isotope is defined as the time taken for its radioactivity to fall by half.
(1 mark)
ii) Nuclei with the same number of protons but a different number of neutrons isotopes.
(1 mark)
b) Student’s graph.
(4 marks)
21
GCSE Physics for CCEA second edition
c) Half-life = 21 days
(2 marks)
d) Three weeks is 1 half-life. So one half-life BEFORE arrival, the mass of the uranium present
in the sample would be double what it was when it arrived; so the mass of uranium present
(2 marks)
would have been 2 x 100 = 200 grams.
5. One hour is 60/12 = 5 half lives, so proportion left after 1 hour is 1/25 = 1/32 of material.
(3 marks)
6. Radioactivity is a spontaneous, random process governed by the laws of probability. Just as one
is unlikely to obtain exactly 3 heads from 6 tosses of a fair coin, so the count from a long half(2 marks)
life source is unlikely to be exactly the same in each of four 10 second intervals.
22
GCSE Physics for CCEA second edition
Chapter 5 Waves, sound and light
In-text questions
1. a) Energy flows from A towards B.
b) In a longitudinal wave, X vibrates parallel to the axis of the slinky.
c) In a transverse wave, X vibrates perpendicular to the axis of the slinky.
d) Another example of a transverse wave is a water wave.
2. a)  = 60 ÷ 4 = 15 cm
b) number of waves pass the marker in 1 second = 10 ÷ 4 = 2.5
c) 2.5 Hz
d) v = f = 2.5 Hz x 15 cm = 37.5 cm/s
3. a) A lightning flash is generally seen before thunder is heard because light travels faster in air
than sound.
b) distance = speed x time = 330 m/s x 4 s = 1320 m
4. total distance travelled by sound = speed x total time = 330 m/s x 6 s = 1980 m
distance to cliff = ½ x total distance = ½ x 1980 = 990 m
5. a)
Frequency (Hz)
Wavelength (m)
680
0.5
440
1.0
170
2.0
136
2.5
85
4.0
68
5.0
1/Wavelength (m1
)
2.0
1.0
0.50
0.40
0.25
0.20
b) Graph: line of best fit is a straight line through the origin.
c) Incorrect point is (1.0, 440)
d) directly proportional
e) The value of f for all table values (except the second) is 340 m/s.
6. a) wavelength = 14 cm ÷ 6 = 2.33 cm
b) distance between ripple A and ripple F = 2.33 x 5 = 11.65 cm
speed of waves 
frequency 
distance
11.65
= 1.165 cm/s

time
10
speed
1.165

= 0.5 Hz
wavelength
2.33
23
GCSE Physics for CCEA second edition
7.
Property
On reflection from deep water into
shallow water
On reflection from a barrier
Increases/Decreases/Does not change
Increases/Decreases/Does not change
Wavelength Decreases
Does not change
Frequency
Does not change
Does not change
Speed
Decreases
Does not change
8. 0°
9. 50°
10. 65°
11.
So that motorists will see the word “AMBULANCE” when they see the ambulance in their rearview mirrors.
12. Angle of reflection at M1 is 30o, so angle between reflected ray and M1 is 60o.
Angle between incident ray to M2 and mirror M2 is 30o, so angle of incidence at M2 is 60o.
Angle of reflection at M2 is 60o. The ray incident on M1 is parallel to the ray reflected from M2.
13. 0°. The ray is reflected back along the path of the incident ray.
14. i) Light is fastest in air.
ii) Light is slowest in B. (Light bends towards normal when it leaves air and enters B, so light is
slower in B than in air. Light bends away from the normal when it leaves B and enters A, so
light is faster in A than in B. Light bends even further away from the normal when it leaves
A and enters air, so light is faster in air than in A.)
15. See Figure 29 on page 92.
16. a) Ray diagram similar to first diagram in table on page 96.
b) Image is 6 cm from lens, but on same side as the object.
c) Image is enlarged, erect and virtual.
17. Focal length is 12 cm.
18. a) Minimise exposure to sunlight by remaining indoors when sun is hottest. Use high sun
protection cream (high SPF cream) on skin when in sunshine.
b) To detect forgeries of banknotes and to kill bacteria in water chillers.
19. a) Infra red light is used in toasters in kitchens and in PIR (passive infra red) systems to detect
intruders and burglars.
b) Infra red light can burn the skin.
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GCSE Physics for CCEA second edition
20. Electromagnetic waves can travel in a vacuum; in a vacuum all electromagnetic waves travel at
the same speed.
21. a) radio waves
b) X-rays
22. speed = f = 200 000 Hz x 1500 m = 300 000 000 m/s = 300 000 km/s
900
distance
time 

= 0.003 s
speed
300000
Exam questions (pages 105–7)
1.
a) i) The diagram shows 3 complete wavelengths cover 60 m. Each wavelength is therefore
60/3 = 20 m.
(1 mark)
ii) Frequency is the number of waves passing a fixed point in 1 second.
(1 mark)
iii) frequency = number of waves passing in 1 second = 10/25 = 0.4 Hz
(1 mark)
iv) v = f = 0.4 x 20 = 8 m/s
(1 mark)
b) i) See page 79.
(1 mark)
ii) See page 79.
(2 marks)
iii) The reflected waves have been refracted as they pass from deep water into shallow water.
In shallower water they have a smaller speed, but an unchanged frequency. They
therefore have a smaller wavelength, so their wavefronts are closer together. (2 marks)
2. a) i) Vibrating
(1 mark)
ii) The skin is vibrating with a larger amplitude.
(1 mark)
iii) The cone is making more vibrations per second.
(1 mark)
b) i) He could become deaf (or become hard of hearing).
(1 mark)
ii) They could fit double (or triple) glazed windows in their homes.
(1 mark)
c)
Statement
Can cause sunburn and skin cancer
Can heat food
Have the greatest wavelength
3. a) i) Dispersion
ii) See Figure 30 on page 92.
Waves
Ultraviolet
Infrared or microwaves
Radio wave
(2 marks)
(1 mark)
(2 marks)
iii) Each colour in white light travels at a different speed in glass and therefore each colour
bends by a different amount. Red slows down least and violet slows down most.
(2 marks)
b) i) See page 99.
(2 marks)
25
GCSE Physics for CCEA second edition
ii) See page 99.
(1 mark)
iii) f = 2.7 cm
(1 mark)
iv) Magnified and upside down
(3 marks)
4. a) The first sound Tom heard came directly from Sean 200 m away. The second sound was the
echo from the cliff. In this case the sound travelled 350 m to the cliff and the reflected echo
traveled a further 150 m back to Tom.
(2 marks)
distance
speed
Tom hears the first sound after 200/340 = 0.588 seconds. Tom hears the second sound after
500/340 = 1.471 seconds. Time interval = 1.471 – 0.588 = 0.883 seconds.
(5 marks)
b) time 
5. a) A: Transverse; B: Longitudinal.
(2 marks)
b) Energy
(1 mark)
c) X vibrates vertically, at 90° to the direction in which the wave is travelling.
(2 marks)
d) 0.3 m
(1 mark)
e) 0.4 m
(1 mark)
f) 3 Hz
(1 mark)
g) v = f = 3 x 0.4 = 1.2 m/s
(3 marks)
6. a) A transverse wave is one in which the particles vibrate at 90° to the direction in which the
wave is travelling.
(2 marks)
b) X-rays – Detects broken bones
Ultra-violet light – Detects banknote forgeries
Infra-red light – Night-time photography
Radio waves – Long distance communications
Microwaves – Fast food preparation
7. a) See text.
(5 marks)
(1 mark)
b) angle of incidence = angle of reflection = 63°
(2 marks)
c) Reflected ray from M2 is parallel to incident ray on M1
(2 marks)
26
GCSE Physics for CCEA second edition
Chapter 6 Electricity
In-text questions
1. a) Static electricity is the study of stationary charges.
b) Positive and negative charges.
c) Like charges repel, unlike charges attract.
2. a) Free electrons move from the cloth (which is now deficient of negative charge and so
becomes positively charged) to the polythene cloth (which now has an excess of free
electrons and so becomes negatively charged).
b) Charging by friction.
3.
Material of rod
Bead movement
Positive
Perspex
Cellulose acetate
Polythene
Steel
Repelled
Repelled
Attracted
None
Charge on rod
Negative
Uncharged
✓
✓
✓
✓
4. a) Useful: photocopier; paint spraying of cars.
b) Nuisance: clothes stick together when removed from tumble dryer; ‘shocks’ from walking
across a nylon carpet and then touching door handle.
c) Dangerous: being struck by lightning; refuelling aircraft.
5. a) 3.0 A = 3000 mA
b) 0.2 A = 200 mA
6. a) 400 m A = 0.4 A
b) 1500 m A = 1.5 A
7. a) current = 6 A, time = 10 s, charge = ?
charge = current x time
= 6 A x 10 s
= 60 C
b) current = 300 m A = 0.3A, time = 1minute = 60 s, charge = ?
charge = current x time
= 0.3 A x 60 s
= 18 C
8. a) current = ?, time = 5 s, charge = 100 C
charge = current x time
100 C = current x 5 s
current = 100 ÷ 5 = 20 A
27
GCSE Physics for CCEA second edition
b) charge = 500 mC = 0.5 C, time = 50 s, current = ?
charge = current x time
0.5 C = current x 50 s
current = 0.5 ÷ 50 = 0.01 A
c) charge = 60 μC = 0.000006 C, time = 200 s, current = ?
charge = current x time
0.000006 C = current x 200 s
current = 0.000006 ÷ 200 = 0.3 x 10-6 A = 0.3 μA
9. Two volts means 2 joules of energy are supplied to each coulomb of charge that the cell supplies.
10. energy = 9 J, charge = 6 C, voltage = ?
energy
9
voltage 
 = 1.5V
charge
6
11. energy = ?, charge = 3 C, voltage = 18 V
energy
voltage 
charge
energy
18 
3
energy = 18 x 3
= 54 J
12. energy = 150 J, charge = 25 C, voltage = ?
energy
150
voltage 

=6V
charge
25
13. a) Voltmeter, since it is in parallel.
b) 12 V = 5V + ?
? = 12 – 5
= 7V
c) 12 V means 12 joules of energy are supplied to each coulomb of charge.
d) 7 volts are dropped across motor, therefore 7 joules of energy are deposited by each coulomb
of charge that passes through the motor.
14. a)
b)
15. a) Light Dependent Resistor
b)
c) The resistance of an LDR decreases when light is shone on it.
28
GCSE Physics for CCEA second edition
16. current = ?, resistance = 10 Ω, voltage = 20V
V = IxR
20V = I x 10 Ω
I = 20V ÷ 10 Ω = 2 A
17. current = 3 A, resistance = ?, voltage = 15 V
V= IxR
15V = 3 A x ?
R = 15 V ÷ 3 A = 5 Ω
18. current = 2 A, resistance = 25 Ω, voltage = ?
V= I x R
= 2A x 25 Ω
= 50 V
19. a) current = 2.5 A, resistance = ?, voltage = 15 V
V= IxR
15V = 2.5 A x R
R = 15 V ÷ 2.5 A = 6 Ω
b) current = 2 A, resistance = 6 Ω, voltage = ?
V= IxR
V = 2A x 6 Ω
= 12 V
20. a) current = ?, resistance = 12 Ω, voltage = 6V
V = IxR
6V = I x 12 Ω
I = 6V ÷ 12 Ω = 0.5 A
b) current = 15 A, resistance = 12 Ω, voltage = ?
V=IxR
V = 1.5A x 12 Ω
= 18 V
21. current = 100mA = 0.1 A, resistance = ?, voltage = 6 V
V= IxR
6V = 0.1 A x R
R = 6 V ÷ 0.1 A = 60 Ω
29
GCSE Physics for CCEA second edition
22. a)
b) No. Graph is non-linear which is necessary for Ohm’s Law.
23. a)
30
GCSE Physics for CCEA second edition
b) No. Graph is non-linear.
c)
Voltage in V
Current in mA
Resistance in Ω
0
0
0
0.1
0.2
0.3
0.4
0.5
0.6
0.1
0.1
0.1
0.1
1.5
73
1000 2000 3000 4000 333.3 8.219
0.9
250
2.8
24. a) Simple series circuit
R = R1 + R2
= 6 Ω+ 5 Ω
= 10 Ω
b) Simple parallel circuit
1
1
1


R T R1 R 2
1 1
2
1
 


6 6
6
3
RT = 3 Ω
c) Simple series circuit
RT = R1 + R2 + R3
=2Ω+4Ω+6Ω
= 12 Ω
d) Simple parallel circuit
1
1
1


R T R1 R 2
1 1
3
1
 


12 6
12
4
RT = 4 Ω
 product 
e) R T  
  R3
 sum 
=2+1
=3Ω
 1
1 
  R 3
f) R T  

 R1 R 2 
4 4
RT      5
4 4
=2+5
=7Ω
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GCSE Physics for CCEA second edition
 product 
g) R T  
 3
 sum 
2 2
RT      3
2 2
=7Ω
h) We must do top branch of circuit first: 2 Ω + 2Ω = 4 Ω
 product 
RT  

 sum 
4 4
RT     = 2 Ω
4 4
i)
 product 
RT  

 sum 
3 6
RT     = 2 Ω
3 6
j) In effect, there are three series resistors when we reduce the two parallel networks
 9 18 
4 6
R T     + 1.6 Ω +   
 9 18 
4 6
= 2.4 + 1.6 + 6.0
= 10 Ω
25. The 3 resistors in series = 1 + 2 + 3 = 6Ω
The 3 resistors in parallel:
1
1
1
1



R T R1 R 2 R 3
1 1 1
  
1 2 3
6  3  2 11


6
6
Therefore RT = 6/11 Ω
1 Ω and 2 Ω in parallel with 3 Ω in series = 3 ⅔ Ω
1 Ω and 3 Ω in parallel with 2 Ω in series = 2 ¾ Ω
2 Ω and 3 Ω in parallel with 1 Ω in series = 2 1/5 Ω
1 Ω and 2 Ω in series and in parallel with 3 Ω = 1.5 Ω
1 Ω and 3 Ω in series and in parallel with 2 Ω = 1.33 Ω etc., etc
26. a) i) total resistance = 2 + 4 + 6 = 12 Ω
total voltage = 3V
V 3
total current drawn    0.25A
R 12
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GCSE Physics for CCEA second edition
product 64

4
sum
16
total voltage = 8 V
V 8
total current drawn    2A
R 4
ii) total resistance 
b) The 8Ω resistors are in parallel, so the voltage dropped will be the same voltage ie., 8V.
27. a) i)
12  12
6
12  12
total voltage = 9 V
9
total current   1.5 A
6
A1 = 1.5A
A2 = 0.75A
A3 = 0.75A
total resistance 
6 6 4 4

66 44
=3+2
=5Ω
total voltage = 10 V
V 10
total current  
 2A
R 5
A3 = 2A
A1 = 1A
A2 = 1A
ii) total resistance 
b) Since each 6 Ω resistor is carrying 1 A, there must be the same (V = IR) voltage of 6 Ω x 1A
= 6V across each 6 Ω resistor.
Similarly, since each 4 Ω resistor is carrying 1 A, there must be the same voltage of 4 Ω x 1A
= 4V across each of the 4 Ω resistors.
28. energy = ?, power = 1000 W, time = 1 hr = 3600s
energy = power x time
= 1000 x 3600
= 3 600 000 J
29. a) energy = 15 000 J, power = ?, time = 10 s
energy 15000
power 

= 1500 W
time
10
b) 1500 W = 1.5 kW
30. current = 0.25 A, voltage = 240 V, time = 60 s, energy = ?
E= V x I x t
= 240V x 0.25A x 60s
= 3600 J
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GCSE Physics for CCEA second edition
31. a) energy = ?, power = 960 W, time = 60 s
energy = power x time
= 960 W x 60 s
= 57 600 J
b) current = ?, voltage = 12 V, power = 960 W
P =VxI
960 W = 12 V x I
960
I
= 80 A
12
32. current = 4 A, voltage = 240 V, power = ?
P=VxI
= 240 V x 4A
= 960 W
33. current = ?, voltage = 12 V, power = 48W
P=VxI
48 W = 12 V x I
48
I
=4A
12
34.
Name of appliance
Power rating
Bulb of study lamp
60 W
Television
80 W
Toaster
120 W
Convector heater
2 kW
Shower
3 kW
P
V
Resistance R 
60
 0.25 A
240
80
 0.33 A
240
120
 0.5 A
240
2000
 8.33 A
240
3000
 12.5 A
240
240
 960 
0.25
240
 720 
0.333
240
 480 
0.5
240
 28.8 
8.33
240
 192 
12.5
Current I 
V
I
35. resistance = 48, voltage = 240 V, power = ?
240 2
V2
P

= 1200 W
R
48
36. a) i) Brown.
ii) Blue.
iii) Green and yellow.
b) i) Current will flow from the live wire, through the metal case to the person touching the
case, and then to earth. The person touching the case would be electrocuted.
34
GCSE Physics for CCEA second edition
ii) Since the earth wire is now properly connected, the current will flow through the earth
wire to the ground, melting the fuse, cutting off the current. The person touching the case
would not be electrocuted.
37. a) Direct current – always flows in the same direction, from a fixed positive terminal to the
fixed negative terminal of a supply. See Figure 39 b, page 133.
b) Alternating current – the voltage (and hence the current) change size and direction in a
regular and repetitive way. See Figure 40, page 133.
38. Circuit breakers react much more quickly than fuses so protecting the user.
39. a) current = ?, voltage = 230 V, power = 60W
P=VxI
60 W = 230 V x I
60
I
= 0.26 A
230
b) A fuse rated greater than 3 A would pass too high a current which would be dangerous.
40. a) current = ?, voltage = 240 V, power = 3000W
P=VxI
3000 W = 240 V x I
3000
I
= 12.5 A i.e. the fuse would ‘blow’.
240
b) current = ?, voltage = 240 V, power = 60 W
P=VxI
60 W = 240 V x I
60
= 0.25 A
I
240
If a 13 A fuse was used, the fuse would not ‘blow’ until the current exceeded 13 A. So a
faulty study lamp would electrocute user.
c) current = ?, voltage = 240 V, power = 800 W
P=VxI
800 W = 240 V x I
800
I
= 3.33 A
240
So a 5A fuse would be preferable.
41. Consider 1 bulb:
current = ?, voltage = 240 V, power = 60 W
P=VxI
60 W = 240 V x I
60
I
= 0.25 A
240
So you should use less than 20 bulbs so that the fuse would not be overloaded.
35
GCSE Physics for CCEA second edition
42. a)
Device
Kettle
Power (W)
2400
Washing Machine
3000
Television
800
Toaster
1300
Current drawn (A)
2400
 10.43
230
2300
 12.5
230
800
 3.48
230
1300
 5.65
230
So total current drawn = 32.06 A
b) Total current drawn (32.06 A) is much greater than the 13 A fuse in extension lead, so the
fuse would ‘blow’ and none of the appliances would work.
43. energy (in kW h) = power (in kW) x time (in hours)
a) energy = 0.1 kW x 12 hr
= 1.2 kWh
b) energy = 0.25kW x 4 hr
= 1 kWh
c) energy = 2.4 kW x 1/12 hr
= 0.2 kWh
44. Lamp: 1.2 kWh @ 12p per unit = 14.4p
Television: 1 kWh @ 12p per unit = 12p
Kettle: 0.2 kWh @ 12p per unit = 24p
45. a) current = 15 A, voltage = 230 V, power = ?
P=VxI
= 230 V x 15 A
= 3450 W
b) number of units used = power (in kW) x time (in hr)
= 3.45 kW x 0.166 hr
= 0.575 units @ 12p per unit
= 6.9p
Exam questions (pages 139–42)
1. a) Lightning strike would mean a large current would flow through building to earth. Fire or
destruction of buildings could happen.
(2 marks)
b) i) Friction between balloon and cloth cause electrons to move from the balloon to the cloth.
The balloon would have a deficiency of electrons and hence would become positively
charged.
(3 marks)
ii) The charges on the balloons are both positive hence the balloon repel each other. Like
charges repel.
(4 marks)
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GCSE Physics for CCEA second edition
c) i)
X
(3 marks)
ii) The currents decreased.
(1 mark)
 63 
R Total  8  

 6  3
=8+2
= 10 Ω
(4 marks)
d) i)
ii) I 
5
V

= 0.5 A
R 10
(3 marks)
iii) V = IR = 0.5 x 8 = 4 V
(3 marks)
iv) power = V x I
= 4 V x 0.5 A
=2W
(4 marks)
v) Since there are 4 V across the 8 Ω resistor then there must be (5 – 4) V = 1 V across the
6Ω resistor.
(2 marks)
vi) One volt, since resistors in parallel have the same voltage across them.
2. a) i)
(1 mark)
X
(2 marks)
ii) R r 
product
0.6  0.3 0.18


= 0.2 Ω
sum
0.6  0.3
0.9
(3 marks)
iii) Brightness remains the same because the voltage across bulb has not changed. (2 marks)
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GCSE Physics for CCEA second edition
b) i)
A
A
(3 marks)
V
ii)
(4 marks)
iii) 70 mA
iv) R 
(1 mark)
0.4
V

=8Ω
I
50
v) Yes, gradient is constant.
(4 marks)
(2 marks)
vi) To keep temperature of wire as low as possible, otherwise resistance would increase.
(1 mark)
3. a) i)
X
X
(4 marks)
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GCSE Physics for CCEA second edition
ii) Parallel.
(1 mark)
iii) Bulbs in parallel will have 1.5 V across each of them i.e. 1.5V in this case. So when one
bulb is removed, the second bulb will still have 1.5 V across it, so its brightness will not
change.
(2 marks)
iv) voltage = 1.5 V, current = 0.3 A, resistance = ?
V = IR
1.5 = 0.3 x R
1.5
R
=5Ω
0.3
b) i) 3 V
(4 marks)
(2 marks)
ii) voltage = 3 V, current = ?, resistance = 5 Ω
V = IR
3=Ix5
3
I  = 0.6 A
5
iii) Bulb will be brighter.
(4 marks)
(2 marks)
c) i) The resistance increases because length of resistance wire increases.
ii) Current decreases as the resistance has increased.
(2 marks)
(2 marks)
4. a) i)
A
X
V
0.5
V
=5Ω

I
0.1
V 3.2
R

=8Ω
I
0.4
(2 marks)
ii) R 
(3 marks)
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GCSE Physics for CCEA second edition
iii)
(2 marks)
iv) The gradient of the graph increases as the current increases because the resistance of bulb
filament increases as the current increases. The reason for this is that temperature of the
filament wire increases.
(2 marks)
b) i) power = 2000 W, voltage = 240 V, current = ?
P=VxI
2000 W = 240 V x I
2000
I
= 8.33 A
240
Fuse size = 13 A
(4 marks)
ii) live = 8.33 A; neutral = 8.33 A; earth = 0 A
(1 mark)
iii) A current of up to 13 A would flow through person touching casing of fire.
(1 mark)
iv) Earth wire should be connected to metal body of electric fire.
(1 mark)
v) The fuse must be connected to live wire.
(1 mark)
vi) The 13 A current would flow through fuse and earth wire to ground. The fuse will blow
isolating the device from the high voltage.
(1 mark)
5. a) i) 12107 – 11847 = 210 units
ii) 1 unit = 12 p
210 units = 210 x 12 = 2520 p = £25.20
b) i) A = fuse
(1 mark)
(2 marks)
(1 mark)
ii) 2
(1 mark)
iii) 1 = blue; 2 = brown
(2 marks)
c) i) As thickness increases, resistance decreases.
(2 marks)
ii) As length increases, resistance increases.
(2 marks)
d) i) Draw lines to connect points 1 to 2 and 4 to 6; or draw lines to connect points 1 to 3 and 4
to 5.
(2 marks)
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GCSE Physics for CCEA second edition
ii) The current flows from positive terminal to 1 to 2 to 6 to 4 to the negative terminal.
(2 marks)
e) i) Parallel.
ii) R r 
product
55
25


= 2.5 Ω
sum
5  5 10
(1 mark)
(2 marks)
iii)
(1 mark)
6. a) i) 240 V means 240 J deposited by each coulomb of charge that passes through TV. 80 W
means 80 J of energy consumed by the TV in each and every second.
(2 marks)
ii) power = 80 W, voltage = 240 V, current = ?
P=VxI
80 W = 240 V x I
80
I
= 0.33 A
240
(3 marks)
iii) 1 A fuse would be the safest size of fuse to select. The other fuses will allow currents
which would be too large.
(2 marks)
iv) voltage = 240 V, current = 0.33 A, resistance = ?
V = IR
240 = 0.33 x R
240
R
= 720 Ω
0.33
(3 marks)
v) Blue wire to the left pin and brown wire to the right pin.
(3 marks)
vi) The live wire.
(1 mark)
vii) To isolate the appliance and user from high voltage.
(1 mark)
viii)All the live electrical wires and circuits inside the TV are insulated by the non-metallic
casing of the TV.
(3 marks)
b) i) energy = power x time
=8x2
= 16 units @ 12p per unit
= 192 p
= £1.92
(3 marks)
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GCSE Physics for CCEA second edition
ii) 15m means resistance will be 3 times bigger. Similarly the cross-sectional area will be 3
times bigger, therefore the resistance will be 3 times smaller. The combined effect is that
the resistance will be the same as before i.e., 0.045 Ω.
(6 marks)
iii) The current is small in the cables so that the (I2 R) heating effect is smaller.
(2 marks)
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GCSE Physics for CCEA second edition
Chapter 7 Electromagnetism
In-text questions
1. a) Use a larger current; use more turns of wire; put a soft iron rod into the middle of the
solenoid.
b) Lifting and dropping magnetic materials like iron and steel in scrap yards.
2. a) The direction of the magnetic lines of force are from the N-pole of the magnet to the S-pole.
b) The brass rod will move to the right, parallel to the brass rails.
c) The brass rod will move to the left.
d) Assuming the magnet is also in its original position i.e., as in part (a), the brass rod will move
to the left.
3. a) ‘d.c.’ means direct current.
b) The direction of the force on AB is vertically downwards.
c) The direction of the force on CD is vertically upwards.
d) The forces form a couple which results in a clockwise moment about the axis, causing the
coil to rotate.
e) The force on side BC is zero, since the current in BC is parallel to the magnetic field lines.
4. a) There is a rate of change of flux (magnetic field lines) cutting which induces an e.m.f. which
results in an induced current.
b) The induced current will flow in the opposite direction.
c) Julie should move the wire faster.
d) No current will be induced because the wire is moving parallel to the magnetic field lines and
is no longer cutting the field lines.
5. Power is transmitted at high voltage to minimise the current in the cables which reduces heat
losses, sometimes referred to as ohmic losses, in the transmission system.
6. a) Primary coil; soft-iron laminated core; secondary coil.
b) The core transfers energy, in the form of an oscillating magnetic field, from the primary coil
to the secondary coil.
c) Soft iron is the best material for magnetic field lines to pass through.
7. If d.c. was used there would be no changing magnetic field produced by the primary coil,
consequently there would be no induced e.m.f. in the secondary coil.
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GCSE Physics for CCEA second edition
8. VP = 240 V, Vs = 48 V, NP = 2000 turns, Ns = ?
VP N P
240 2000


48
NS
VS N S
2000  48
= 400 turns
NS 
240
9. VP = 4 V, Vs = ?, NP = 20 turns, Ns = 80 turns
VP N P
4 20


VS 80
VS N S
4  80
= 16 V
VS 
20
10. a) Step-down transformer.
b) All electrical appliances in the home operate at 240 V, 24000 V would seriously damage
appliances and would be a health hazard to the occupants.
c) Current in the supply cables would be very large causing a lot of electrical energy to be
wasted as heat energy.
d) VP = 24 000 V, Vs = 240 V, NP = 5000 turns, Ns = ?
VP N P
24 000 5000


240
NS
VS N S
5000  240
= 50 turns
NS 
24 000
11. a) Step-up transformer.
b) VP = 25 000 V, Vs = 400 000 V, NP = 1000 turns, Ns = ?
VP N P
25 000 10 000


400 000
NS
VS N S
10 000  400 000
NS 
= 160 000 turns
25 000
c) The voltage is 400 000 V to reduce the current in the grid. This reduces the energy losses in
the form of heat so that more electrical energy reaches factories and homes.
Exam questions (pages 157–9)
1. a) There is a rate of change of flux linkage between the magnetic field of the magnet and the
coil of copper wire.
(2 marks)
b) Current is alternating. The flux linkage increases and decreases inducing a voltage which
changes in size and direction as long as the magnet is oscillating up and down.
(2 marks)
c) See Figure 39 b, page 133.
(2 marks)
2. a) i) a.c. stands for alternating current. Alternating means that the polarity of the supply
changes sign periodically whereas direct means that the polarity remains constant.
(3 marks)
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GCSE Physics for CCEA second edition
ii) Soft iron.
iii) VP = 16 V, Vs = ?, NP = 100 turns, Ns = 50 turns
VP N P
16 100


VS 50
VS N S
16  100
= 32 V
VS 
50
b) i) 10 steps = 20 V
1 step = 2 V
So voltage will increase or decrease by 2 V.
ii) 1 step = 50 turns
10 steps = 500 turns
iii) VP = 240 V, Vs = 20 V, NP = ?, Ns = 500 turns
VP N P
240 N P


20 500
VS N S
500  240
= 6000 turns
NP 
20
(1 mark)
(4 marks)
(3 marks)
(1 mark)
(3 marks)
iv) If a current flows which is greater than the fuse rating, the fuse will ‘blow’ protecting the
device to which it is connected.
(2 marks)
c) i) Kinetic energy of fission fragments is converted into heat energy.
(2 marks)
ii) X = generator which converts rotational kinetic energy into electrical energy. (2 marks)
d) i) Step-up; step-down.
ii) High; low.
(2 marks)
(2 marks)
iii) High voltages are used to minimise current in the grid. This reduces electrical energy lost
as heat energy.
(2 marks)
3. a) i) See Figure 6, page 144.
(2 marks)
ii) See Figure 6, page 144.
(4 marks)
b) i) See Figure 24, page 155.
ii) a.c. voltages.
iii) VP = 6 V, Vs = 12 V, NP = 200 turns, Ns = ?
VP N P
6 200


12 N S
VS N S
200  12
NS 
= 400 turns
6
(7 marks)
(1 mark)
(4 marks)
c) The output of a power station is a high current and relatively low voltage. If this form of
energy was transmitted directly, without a step-up transformer, the large current would
generate a large amount of electrical energy in the form of heat, lost to the atmosphere.
Hence there would be less energy transmitted to users.
(4 marks)
45
GCSE Physics for CCEA second edition
4. a) i) 25 kJ of energy per coulomb.
(1 mark)
ii) Stepping up the voltage, decreases the current in the grid. This has the effect of
decreasing the electrical energy lost as heat due to the resistance of the cables in the grid.
(2 marks)
iii) Step-down transformers must also be used before electrical energy is put into factories
and homes.
(1 mark)
iv) For safety.
b) i)
energy (in kWh) = power (in kW) x time (in hours)
= 0.8 kW x 0.25 hr
= 0.2 kWh
ii) 1 unit costs 12p, 0.25 units costs 3p
c) i) 1) Momentary deflection in current meter.
2) Momentary deflection in the opposite direction in current meter.
ii) The needle in the current meter will oscillate at 1 Hz.
(1 mark)
(4 marks)
(1 mark)
(1 mark)
(2 marks)
(2 marks)
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GCSE Physics for CCEA second edition
Chapter 8 The Earth and Universe
In-text questions
1. asteroid, planet, star, galaxy, Universe.
2. a) The light from distant galaxies has a longer wavelength than we would have expected.
Having a longer wavelength means that it is closer to the red end of the visible spectrum.
This is called ‘red-shift’.
b) These galaxies are moving away from our galaxy (the Milky Way).
3. Mercury, Venus, Earth, Mars, Jupiter, S aturn, Uranus, Neptune.
4. The heliocentric (Sun-centred) model explains:
 the apparent ‘looping’ of planets was due to the combined motion of the Earth and the planet
itself;
 why Venus is sometimes closer to Earth than Mars so it appears brighter, but at other times
Venus is further away than Mars and appears less bright;
 why Venus and Mercury should show phases, just as our Moon does.
5. The Big Bang occurred between 13 and 14 billion years ago. It was then that the Universe
(matter, energy and time) came into existence. The Big Bang (or explosion) came from a tiny
point that physicists call a singularity.
6. In order to explain the expansion of the Universe, Steady State theory suggests that matter is
being created continually. Physicists are uncomfortable with this idea because it suggests that our
thoughts about energy conservation might not be correct. In addition, the theory fails to explain
why the Universe is expanding or why there is cosmic microwave background radiation.
7. At temperatures around 15 million Celsius, hydrogen nuclei collide with each other at
unbelievably high speeds. At such speeds they can form new, heavier nuclei such as helium-3
and helium-4. This process is called nuclear fusion and results in the production of vast
quantities of heat and light energy. It occurs in stars.
8. Clouds of gas and dust come together as a result of mutual gravitational attraction, but do not
have enough material for the temperature to reach 15 million °C to form a star. Such gas and dust
clouds are called planetary nebulae and eventually they become planets as a result of accretion
due to gravitational attraction. The presence of a massive star may cause them to become trapped
in its orbit. Since the gas and dust clouds originally spiralled in the same direction, so the planets
would orbit the Sun in same direction and in the same plane.
9. Currently astrophysicists estimate the age of the Universe to be 13.75 billion years.
10. When rock strata of similar ages are studied in various countries, they show remarkable
similarity – suggesting that these countries were joined together when the rocks formed. The
most compelling evidence in favour of continental drift comes from the magnetic orientation of
the rocks in under-ocean ridges. As the liquid magma erupts out of the gap, the iron particles in
the rocks tend to align themselves with the Earth’s magnetic field, and as it cools they set in that
position. Every half million years or so, the Earth’s magnetic fi eld tends to swap direction. This
means the rocks on either side of the ridge have bands of alternate magnetic polarity.
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GCSE Physics for CCEA second edition
11. Earthquakes are caused when tectonic plates slide past each other. This happens where the plates
meet.
12. The Earth’s lithosphere is the lower part of the crust and the upper, solid part of the upper
mantle.
13. Every century the continents move apart by 1.2 cm x 100 = 120 cm =1.2 m. In 50 000 centuries
they move apart by 50 000 x 1.2 m = 60 000 m = 60 km
Exam questions (pages 175–6)
1. a) i) Nebula.
(1 mark)
ii) Hydrogen and dust.
(1 mark)
iii) It compresses under its own gravity and its temperature rises appreciably.
(1 mark)
iv) A star.
(1 mark)
b) i) Nuclear fusion.
ii) Heat.
(1 mark)
(1 mark)
2.
Planet
Earth
Jupiter
Mercury
Venus
Uranus
Neptune
Mars
Saturn
Distance from Sun in millions of kilometres
150
778
58
108
2870
4497
227
1247
(4 marks)
3. a) Universe.
b) i) Neptune.
(1 mark)
(1 mark)
ii) C.
(1 mark)
iii) D and E.
(1 mark)
iv) Jupiter, Saturn, Uranus, Neptune.
(2 marks)
c) Nuclear fusion.
(1 mark)
d) The journey would take a very long time. There are logistics problems in carrying enough
fuel, oxygen, food and water for the journey.
(2 marks)
e) Steady State theory.
(1 mark)
f) i) The Big Bang occurred between 13 and 14 billion years ago. It was then that the
Universe (matter, energy and time) came into existence. The Big Bang (or explosion)
came from a tiny point that physicists call a singularity.
(1 mark)
48
GCSE Physics for CCEA second edition
ii) The Universe is continuing to expand.
(1 mark)
4. a) Our present model is heliocentric. This means the planets orbit the Sun. The ancient theory
was geocentric. This means that the planets and the Sun orbited the Earth. In our present
model there are 8 planets. The ancient theory had only 6 planets because Uranus and Neptune
had not yet been discovered.
(2 marks)
b) Stars form when clouds of hydrogen, known as a stellar nebula, come together because of
gravity. As these clouds become more and more compressed, they start to spiral inwards and
the temperature rises enormously. Gravity eventually compresses the hydrogen so much that
the temperature reaches about 15 million °C. At this temperature, nuclear fusion reactions
start and a star is born. Clouds of gas and dust, called planetary nebulae, come together as a
result of mutual gravitational attraction, Such gas and dust clouds eventually become planets
as a result of accretion due to gravitational attraction.
(2 marks)
c) i) The arrows all point from points 1, 2 and 3 towards the centre of the Sun.
ii) Gravitational attraction between the Sun and the comet.
(3 marks)
(1 mark)
iii) Points 1 and 2 are equidistant from the centre of the Sun and therefore the size of the
force on the comet at these two positions is the same. Point 3 is further from the Sun than
points 1 and 2. At point 3, the force on the comet is less than at points 1 and 2. This is
because gravitational force decreases with distance.
(2 marks)
iv) Kinetic energy.
(1 mark)
v) As the comet approaches the Sun it loses gravitational potential energy. This GPE is
converted into kinetic energy. As it moves away from the Sun it loses KE. The lost KE is
converted into gravitational potential energy.
(1 mark)
vi) The comet is fastest when it is closest to the Sun and slowest when it is furthest away
from the Sun. This is because it has most KE when it is closest the Sun.
(2 marks)
5. a) The light from distant galaxies has a longer wavelength than we would have expected.
Having a longer wavelength means that it is closer to the red end of the visible spectrum.
This is called ‘red-shift’.
(1 mark)
b) Red shift tells us that these galaxies are moving away from our galaxy (the Milky Way).
(2 marks)
6. a) i) Red shift.
ii) Away from our galaxy.
(1 mark)
(1 mark)
b) Big Bang Theory.
(1 mark)
c) See answer to question 4(b).
(4 marks)
d) The temperature near the centre of the Sun is so high that hydrogen nuclei collide with each
other at unbelievably high speeds. When they collide at such speeds they can form new,
heavier nuclei such as helium-3 and helium-4. This process is called nuclear fusion and
results in the production of vast quantities of heat and light energy.
(3 marks)
49

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