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An swer s: 1. Motion
Additional Science: Pages 166–167
Physics: Pages 108-109
Distance–time graphs
Speed
P2 1.1 Distance–time graphs
What does the gradient line on a
distance–time graph represent?
Speed
On a distance–time graph for a car,
what happens to the line on the
graph when the speed is increased?
The line gets steeper (its gradient is increased).
How could we tell from the graph if
the car was stationary?
The line would be horizontal.
What is the scientific unit of speed?
metre per second, or m/s
Write down the equation for
calculating the speed of an object
moving at constant speed.
Speed =
distance
time
Why are long-distance vehicles fitted
To check that their drivers don’t drive for too long
with tachographs?
Speed in action
How can you use a distance–time
graph to calculate the speed a lorry
was travelling at?
Learning Grids for GCSE AQA A Physics 2
By dividing the distance travelled over the time taken
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Additional Science: Pages 168–169
Physics: Pages 110-111
Velocity
Acceleration
P2 1.2 Velocity and acceleration
What is velocity?
Velocity is speed in a given direction.
Why does the velocity of a plane
change as it ‘loops the loop’ at
constant speed?
The direction of motion changes constantly, so its velocity also changes constantly.
What is acceleration?
The change of velocity per second
What is the scientific unit of
acceleration?
metre per second squared (m/s²)
Write down the equation used to
calculate acceleration.
Acceleration =
In the alternative equation
a = (v-u)/t, what do the letters ‘u’
and ‘v’ represent?
u is the initial velocity, and v is the final velocity.
What is deceleration?
Deceleration is the change in velocity per second when an object slows down.
Give another name for deceleration.
Negative acceleration
change in velocity
time taken
Deceleration
Learning Grids for GCSE AQA A Physics 2
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Additional Science: Pages 170–171
Physics : Pages 112-113
Investigating acceleration
P2 1.3 More about velocity–time graphs
When an object is accelerating, why
does the line on its velocity–time
graph go up?
Because its velocity is increasing with time
How can we tell from a velocity–
time graph whether the acceleration
of an object was constant?
The line would be straight.
What does the gradient of a line on a
Acceleration
velocity–time graph represent?
Braking
(HIGHER)
Using the area under the
line
What would the line look like on a
velocity–time graph for an object
moving at constant speed?
It would be straight and horizontal.
If the line goes down, what does this
tell us about the motion of the
object?
It’s slowing down, or decelerating.
How do we find the distance
travelled from a velocity–time
graph?
By calculating the area under the line
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Additional Science: Pages 172–173
Physics : Pages 114-115
P2 1.4 Using graphs
Look at the following graph, drawn
for an object moving at constant
speed.
1) Height represents distance travelled.
1) What does the height of the
triangle represent?
Using distance–time graphs
2) Write down the equation for
finding the gradient of the
diagonal line.
Gradient of the line =
height of the triangle
base of the triangle
An swer s: 2. Fo rces
Using velocity–time graphs
What does the gradient of a
distance–time graph tell us?
The speed of the object
Now use the graph to calculate the
speed of the object.
Speed = gradient of the line = height of the triangle ÷ base of the triangle
= 30 ÷ 10 = 3m/s
What can we tell about the speed of
an object if its distance–time graph
is not a straight line?
The speed of the object is changing.
On a velocity–time graph, what does
the height of the line (or triangle)
represent?
The change of velocity
What does the base of the triangle
represent?
The time taken
Why does the gradient of a velocity–
time graph represent acceleration?
Because acceleration = change of velocity/time taken, which is the same as finding
the gradient of the graph
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Using velocity–time graphs
(cont.)
Using the graph shown, calculate the
acceleration.
Acceleration = change in velocity ÷ time taken = 15 m/s ÷ 5 s = 3 m/s
How would you calculate the
distance travelled from the graph?
Learning Grids for GCSE AQA A Physics 2
By calculating the area under the line, which is the area of the triangle
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Additional Science: Pages 176–177
Physics : Pages 118-119
Forces between objects
P2 2.1 Forces between objects
What happens when you apply a
force to squeeze a tube of
toothpaste?
The tube changes its shape and pushes toothpaste out of the tube.
What happens when you apply more
force?
The toothpaste comes out faster.
1) Change its shape
Name three things that forces can do
to an object.
2) Change its state of rest
3) Change its motion
Equal and opposite forces
When two objects push or pull on
each other, what can you say about
the forces acting?
They exert equal and opposite forces on one another.
What is the unit of force?
The newton (N)
If a kick-boxer kicks his opponent
with a force of 60 N, what force will
he experience?
A reverse force of 60 N
When a tractor is used to pull a car
out of the mud, which force must be
greater than the force of the mud on
the car?
The force of the ground on the tractor
Why aren’t these forces necessarily
equal to one another?
Because the tractor and the car are not the same
In the mud
Learning Grids for GCSE AQA A Physics 2
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For a moving car, where does
friction act?
Where the tyres are in contact with the ground
Direction of car
Friction in action
Label arrows A and B on the
diagram, showing the friction forces
acting when the car is in motion.
A
Force of road on tyre
What can you say about the two
forces you labelled?
Learning Grids for GCSE AQA A Physics 2
B
Force of tyre on road
They are equal and opposite to one another.
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Additional Science: Pages 178–179
Physics : Pages 120-121
Resultant force
Zero resultant force
Non-zero resultant force
P2 2.2 Resultant force
What is the resultant force on an
object?
A single force that has the same effect as all the forces acting on the object
What happens to a stationary object if
the resultant force on the object is
zero?
The object remains at rest.
What would you observe if the object
was in motion (still with a resultant
force of zero)?
The object would continue to move at the same speed, and in the same direction.
When a heavy box is pushed across
the floor at constant velocity, what
can be said about the resultant force
on the box?
The resultant force is zero.
How can you find the resultant force
on a jet during take-off?
By finding the difference between the thrust force and the force of air resistance on
it
How could the take-off speed be
increased?
By increasing the resultant force (through increasing the thrust force or minimising
the drag force)
When the driver of a race car applies
the brakes, how large is the braking
force compared to the engine force?
The size of the breaking force is greater than the engine force.
Draw an arrow on the diagram to
indicate the direction of the resultant
force that acts when the driver applies
the brakes.
How would you calculate the resultant
By finding the difference between the engine force and the braking force
force acting on the car?
How would you calculate the resultant
force on an object when two forces
By finding the sum of the two forces
are acting in the same direction?
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Additional Science: Pages 180–181
Physics : Pages 122-123
Force and acceleration
P2 2.3 Force and acceleration
If the resultant force on an object is
increased, what will happen to its
acceleration?
Its acceleration will also increase.
Write down the word equation that
links the resultant force, the mass
and the acceleration.
Resultant force = mass × acceleration
Rewrite the word equation using
symbols.
F = ma
Complete the table, giving the name,
symbol and unit for each element of
the equation.
Name
Symbol
Unit
resultant force
F
newtons
mass
m
kilograms
acceleration
a
metres/second²
Using the equation, calculate the
resultant force acting on an object of
F = ma ∴ 2 kg × 3 m/s = 6 N
mass 2 kg and an acceleration of
3 m/s2.
Speeding up or slowing
down
Write down the rearranged version
of the equation used to find
acceleration
a = F/m
True or false: the acceleration of an
object is in the opposite direction to
the resultant force acting on it?
False, it is in the same direction.
What happens to the speed of an
object if the resultant force acts in
the opposite direction to its
velocity?
It decreases.
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Additional Science: Pages 182–183
Physics : Pages 124-125
P2 2.4 On the road
Give two examples of resistive forces
acting on a car in motion.
Forces on the road
1) Friction
2) Air resistance
Write down an equation which can be
used to find the braking force needed Resultant force (braking force) = mass × acceleration
to stop a vehicle.
How does the braking force needed
to stop a vehicle depend on the speed The greater the speed, the greater the braking force needed.
of the vehicle?
What other factor affects the braking
force needed?
The mass of the vehicle
What is the stopping distance of a car? The shortest distance that the car can safely stop in
Stopping distances
Write down the word equation for
finding the stopping distance.
Stopping distance = thinking distance + braking distance
What does the thinking distance
depend on?
The driver’s reaction time
How can the thinking distance be
calculated?
By multiplying the car’s speed by the driver’s reaction time
How can the braking distance be
calculated?
By multiplying the average speed of the car during braking by the braking time
Learning Grids for GCSE AQA A Physics 2
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Factors affecting stopping
distances
For each of the following factors
affecting braking distance, state
whether it increases the thinking
distance or the braking distance.
Tiredness
Thinking distance
Driving a poorly maintained vehicle
Braking distance
Alcohol
Thinking distance
Name two factors which increase
both the thinking and braking
distances.
1) Driving in poor weather conditions
Learning Grids for GCSE AQA A Physics 2
2) Driving a vehicle more quickly
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Additional Science: Pages 184–185
Physics : Pages 126-127
How to reduce your weight
P2 2.5 Falling objects
Where on the Earth can you go if
you want to reduce your weight?
The equator
What will happen to your mass?
It will stay the same.
What is the difference between
weight and mass?
The weight of an object is the force of gravity on an object, whereas the mass is the
quantity of matter in it.
Give the units of weight and mass.
Weight: newtons (N)
What is the unit of gravitational field
strength?
newton per kilogram (N/kg)
What is the value of the Earth’s
gravitational field strength at the
Earth’s surface?
About 10 N/kg
Write down a word equation you
could use to find the weight of an
object.
Weight = mass × gravitational field strength
Rewrite the equation using symbols.
W = mg
Calculate the weight in newtons of a
person of mass 60 kg standing on
the Earth’s surface.
Weight = mass × gravitational field strength ∴ 60 kg × 10 N/kg = 600 N
Learning Grids for GCSE AQA A Physics 2
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Mass: kilograms (kg)
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What is the acceleration of a falling
object acted on only by gravity?
10 m/s²
What is this acceleration known as?
The acceleration due to gravity
How would you find the resultant
force on an object falling through a
fluid?
By subtracting the drag force from its weight
What is the terminal velocity of a
falling object?
The constant velocity the object reaches when the drag force is equal and opposite
to its weight
What is the value of the resultant
force on the object when it has
reached terminal velocity?
Zero
What is the drag force called for an
object moving through air?
Air resistance
The force of falling objects
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Additional Science: Pages 186–187
Physics : Pages 128-129
Stretching and squashing
Elastic energy
Hooke’s law
P2 2.6 Stretching and squashing
What do we mean when we say that
an object is elastic?
It regains its original shape when the forces deforming it are removed.
Give two examples of elastic objects.
1) A rubber band (or spring)
2) A squash ball
A weight is hung from a spring. Write
down a word equation to calculate
Extension of the spring = length of the spring – original length
the extension of the spring.
A graph is drawn of the extension of
the spring against the weight added.
The graph line is straight and goes
through the origin. What does this
tell us?
That the extension of the spring is directly proportional to the weight hung on it
What kind of energy is stored in a
stretched spring?
Elastic potential energy
What happens to this energy when
the spring is released?
The energy is released and transferred into kinetic energy and heat.
What is Hooke’s law?
The extension of a spring is directly proportional to the force applied to it, provided
its limit of proportionality is not exceeded.
What happens when a spring is
stretched beyond its limit or
proportionality?
The spring stretches more than predicted, as the extension is no longer directly
proportional to the force applied to it.
Write down Hooke’s law as an
equation.
Force applied = spring constant × extension
What is the spring constant?
The force per unit extension needed to stretch an object
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Additional Science: Pages 188–189
Physics : Pages 130-131
P2 2.7 Force and speed issues
Why do vehicles use more fuel when
travelling at greater speeds?
Because air resistance at high speeds is much greater than at low speed, and so
more power is needed to maintain a higher speed
Apart from reducing speed, how can
the fuel used by lorries be reduced?
By fitting wind deflectors to the lorries, which decrease their air resistance and
therefore reduce the fuel used
Speed costs
1) The driver is much less likely to be able to stop safely.
Speed kills!
Give two reasons why driving at high
speeds is dangerous to pedestrians.
2) The force on a person struck by a car is much greater if the car is speeding.
Why might a speeding motorist be
discouraged by speed cameras?
Speed cameras catch motorists who are driving faster than the speed limit. They are
then fined and can even lose their licence.
What are average speed cameras?
Speed cameras that are linked to measure the average speed of a vehicle
Why are anti-skid surfaces designed
to be rougher than normal road
surfaces?
The rough surface increases the friction between the tyres and the road, thus
reducing the chance of skidding when a car brakes.
When does skidding usually happen?
When the brakes are applied too harshly
Speed cameras
Anti-skid surfaces
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Additional Science: Pages 192–193
Physics : Pages 134-135
P2 3.1 Energy and work
An swer s: 3. W ork, en erg y and mom entum
What happens to an object when
work is done on it?
A force makes the object move.
When a heavy object is lifted, 10 J of
work is done on it. How much
energy has been transferred to the
object?
10 J
In words, write down the equation
used to calculate the work does by a
force.
Work done = force applied × distance moved in the direction of the force
Working out
Complete the table, giving the
names, symbols and units used in
the equation.
Name
Symbol
Unit
work done
W
joule, J
force
F
newtons, N
distance moved
d
metres, m
How much work is done pushing a
box 2 m across the ground with a
force of 6 N?
Work done = force applied × distance moved ∴ 6 N × 2 m = 12 J
Why do your hands become warm if
you rub them together?
Muscles do work to overcome friction, which is transferred into energy that warms
the hands.
What happens to the kinetic energy
of a vehicle when the brakes are
applied?
It is transferred into heating the brake pads and the wheel discs as well as the
surrounding air.
Friction at work
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Additional Science: Pages 194–195
Physics : Pages 136-137
Gravitational potential
energy transfers
P2 3.2 Gravitational potential energy
What is gravitational potential
energy?
The energy stored in an object due to its position in the Earth’s gravitational field
If 500 J of work is done lifting an
object, how much gravitational
potential energy has the object
gained?
500 J
What happens to the gravitational
energy of the object when it is put
down again?
It decreases.
What two things does the work done 1) The change of height
on an object moving up or down
depend on?
2) The weight of the object
Write down the word equation for
calculating the change of
gravitational potential energy.
Learning Grids for GCSE AQA A Physics 2
Change of gravitational potential energy = weight of the object × change of height
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Why can astronauts lift objects much
Because the gravitational field strength on the surface of the moon is much weaker
more easily on the moon than they
than on the surface of the Earth.
can on Earth?
Fill in the gaps of the following
equation.
Gravitational potential
energy and mass
Change of gravitational
potential energy
=
mass
×
gravitational field
strength
Rewrite this equation using symbols.
EP = m × g × h
Calculate the gravitational potential
energy gained by a ball of mass
0.2 kg when it is lifted 1 m into the
air. The gravitational field strength
on the surface of the Earth is 10
N/kg.
Gain of GPE = mass × gravitational field strength × change of height
= 0.2 kg × 10 N/kg × 1 m
=2J
What is power?
The rate of transfer of energy
What is the unit of power?
watt
Write down a word equation that
could be used to find power.
Power = energy ÷ time
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×
change
of height
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Additional Science: Pages 196–197
Physics : Pages 138-139
Kinetic energy
The kinetic energy formula
Using elastic potential
energy
P2 3.3 Kinetic energy
What two things does the kinetic
energy of an object depend on?
1) The mass of the object
Complete the kinetic energy
equation.
Kinetic energy = ½ ×
What unit is kinetic energy
measured in?
joules, J
What do the letters KERS stand for?
Kinetic energy recovery systems
What are KERS used for?
Storing kinetic energy when cars brake so that it can be used later on
What is elastic potential energy?
The energy stored when work is done on an object.
When firing an arrow from a bow,
what happens to the elastic energy
stored in the bow?
It is transferred into kinetic energy.
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2) The speed of the object
mass
×
speed2
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Additional Science: Pages 198–199
Physics : Pages 140-141
Momentum
P2 3.4 Momentum
How is the momentum of a moving
object calculated?
Momentum = mass × velocity
What is the unit of momentum?
Kilogram metre/second (kg m/s)
Which symbol is used to represent
momentum?
p
Calculate the momentum of a
person of mass 60 kg walking at a
velocity of 4 m/s.
Momentum = mass × velocity
= 60 kg × 4 m/s
= 240 kg m/s
Write down the law of conservation
of momentum.
In a closed system, the total momentum before an event equals the total
momentum after the event.
What happens to the momentum
when a vehicle crashes into the back
of a line of cars?
The momentum is transferred along the line of cars, to the car at the front.
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Additional Science: Pages 200–201
Physics : Pages 142-143
Explosions
Conservation of momentum
Momentum in action
P2 3.5 Explosions
When a skateboarder jumps off his
skateboard, the skateboard flies
away from him. What can you say
about the momentum of the
skateboard?
It is equal and opposite to the skateboarder’s momentum.
Why does the skateboard move
away more quickly than the
skateboarder?
Because the mass of a skateboard is lower than the person
Does momentum have a direction?
Yes
If the total momentum before an
explosion is zero, what will the total
momentum be after the explosion?
Zero
Which scientific law does this
follow?
Conservation of momentum
What happens to the barrel of a gun
when the gun is fired?
The barrel recoils backwards.
How can this effect be minimised in
artillery guns?
By using a spring to slow down the barrel
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Additional Science: Pages 202–203
Physics : Pages 144-145
Impact forces
P2 3.6 Impact forces
What happens to the momentum of
a car during a front-end impact?
It is reduced.
How would a crumple zone at the
front of the car reduce the force of
an impact?
By increasing the impact time, which reduces the impact force
Write down an equation used to
calculate the impact force of a tennis
Impact force = mass × acceleration
ball from its mass and (negative)
acceleration on impact with a racket.
Impact time
Two-vehicle collisions
If the deceleration of the ball is 100
m/s2 when it hits the racket and the
mass of the ball is 0.1 kg, calculate
the impact force on the racket.
Impact force = mass × acceleration
= 0.1 kg × -100 m/s2
= -10 N
When two vehicles collide, what
happens to the total momentum?
It stays the same.
What assumption have you made?
That no external force acts
If a heavy lorry crashes into the back
of a light car, what happens to the
car?
It gains momentum and accelerates forwards.
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Additional Science: Pages 204–205
Physics : Pages 146-147
P2 3.7 Car safety
1) By stopping people from continuing forwards when a car suddenly stops
Clunk click!
Give three ways that seat belts help
to protect people in accidents.
2) By increasing the impact time (reducing the decelerating force)
3) By spreading the force out across the chest
Air bags
Child car seats
What advantage do air bags have
over seat belts?
They spread the force of an impact across the upper part of the body and so the
force is lessened compared with a seat belt.
Who does the child car seat law
apply to?
Children up to 12 years old or up to 1.35 metres in height.
Why was this law brought in?
To reduce deaths and serious injuries of children in cars
Who is responsible for making sure
that children in a car are seated
safely?
The driver
Why do car manufacturers always
include seat belts in their cars?
Because they are required by law
Why do car makers often choose not
to include side impact bars in their
cars?
Because they are not required by law and add to the cost of a new car
Safety costs
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Additional Science: Pages 208–209
Physics : Pages 150-151
P2 4.1 Electrical charges
An swer s: 4. Cur rent electricit y
Electrical charges
What happens when you rub a
balloon with your clothes?
The balloon becomes electrically charged with static electricity.
Why will the balloon then stick to the
ceiling?
The charge on the balloon attracts it to the ceiling.
How does a Van de Graaff generator
charge up?
A rubber belt rubs against a felt pad and charges up. The belt transfers the charge
onto the metal dome.
What happens when the charge on
the dome builds up too much?
Massive sparks are produced.
The Van de Graaff generator
Link each component of an atom with
its charge.
Inside the atom
Proton
Neutral
Electron
Positive
Neutron
Negative
What is the name given to a charged
atom?
An ion
What happens to the charge of an
uncharged atom when you add more
electrons?
It becomes negative.
Why does an uncharged atom become
positive when you remove electrons
Because the atom has fewer electrons than protons
from it?
Charging by friction
Why does rubbing a polythene rod
with a dry cloth make the rod
negatively charged?
Because the dry cloth transfers electrons to the surface of the rod
Would two of these negatively
charged rods repel or attract each
other?
Repel
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Additional Science: Pages 210–211
Physics : Pages 152-153
Electrical circuits
Electric current
P2 4.2 Electrical circuits
What does a circuit diagram show?
It shows how the components in a circuit are connected together.
How can you tell which component
is which?
Each component has its own symbol.
Circle the symbol which represents a
resistor.
What could the other symbol
represent?
A bulb
What is an electric current?
A flow of charge
What determines the size of an
electric current?
The rate of flow of charge
What is the unit of electric current?
Amperes (A)
What is the unit of electric charge?
Coulombs (C)
Write down an equation used to find
the electric current.
Electric current = charge flow ÷ time taken
How can we write the equation
using symbols?
I = Q/t
Calculate the current through a
resistor when a charge of 12 C
passes through it over 2 s.
I = Q/t = 12 C ÷ 2 s = 6 A
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Additional Science: Pages 212–213
Physics : Pages 154-155
Ammeters and voltmeters
P2 4.3 Resistance
Name a component that could be
used to measure the current across
the bulb in an electrical circuit.
Ammeter
What unit is current measured in?
Amperes (A)
What component could be used to
measure the potential difference
across the bulb?
Voltmeter
Write down an equation used to
calculate the potential difference
across the bulb, giving the unit of
each term.
Potential difference across the component (volts) =
When the circuit is switched on, 5 C
of charge passes through the bulb
and 30 J of energy is transferred to
the bulb. Use the equation to
calculate the potential difference
across the bulb.
Potential difference = work done / charge
= 30 J / 5 C
=6V
work done (joules)
charge (coulombs)
The resistance of an electrical
component is defined as resistance =
potential difference ÷ current.
R = V/I
Rewrite this equation using symbols
(letters).
Write down the rearranged versions
of this equation that you would use
to find 1) voltage and 2) current.
Learning Grids for GCSE AQA A Physics 2
1) V = IR
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2) I = V/R
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Write down Ohm’s law.
Current–potential
difference graphs
The current through a resistor at constant temperature is directly proportional to the
potential difference across the resistor.
Complete the current–potential
difference graph for a wire at
constant temperature.
Why is a wire known as an ‘ohmic
conductor’?
Because its resistance is constant
What happens to the potential
difference across a component when The potential difference is reversed.
you reverse the current through it?
What effect would reversing the
potential difference have on the shape
of the line in the graph above?
Learning Grids for GCSE AQA A Physics 2
Reversing the pd would make no difference to the shape of the line.
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Additional Science: Pages 214–215
Physics : Pages 156-157
More current–potential
difference graphs
P2 4.4 More current–potential difference graphs
When an electrical appliance fails,
what is the most likely cause?
Too much current passing through a component in the appliance
Complete the current–potential
difference graph for a filament bulb.
Using current–potential
difference graphs:
a filament bulb
What does the shape of the line on
the graph tell us about the bulb?
The current is not directly proportional to the potential difference, and therefore the
bulb is a non-ohmic conductor.
What happens to the resistance of
the filament bulb as its temperature
is increased?
The resistance increases.
(HIGHER) Why does this happen?
Because the ions in the metal filament vibrate more as the temperature increases.
This causes greater resistance to the passage of electrons through the filament.
What effect does reversing the
potential difference have on the
shape of the line?
It makes no difference; the resistance is the same for the same current, regardless of
its direction.
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Complete the current–potential
difference graph for a diode.
The diode
Current–potential
difference graphs for a
thermistor and LDR
How can we tell from the graph that
a diode is not an ohmic conductor?
The line is curved, which tells us that current is not directly proportional to potential
difference (and so the diode doesn’t obey Ohm’s law).
In the reverse direction, the current
through a diode is very small
compared to the current in the
forward direction. What does this
tell us about the resistance of the
diode?
The resistance in the reverse direction is much higher than in the forward direction.
What happens to the resistance of a
thermistor if the temperature is
increased?
Its resistance decreases.
What does LDR stand for?
Light-dependent resistor
What happens to the resistance of an
LDR when the intensity of light falling
on it is increased?
Its resistance decreases.
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Additional Science: Pages 216–217
Physics : Pages 158-159
P2 4.5 Series circuits
What can you say about the current
passing through components in
series with each other?
The same current passes through each component.
Why is this?
Because the same number of electrons pass through each component every second
What can you say about the
potential difference for components
in a series circuit?
The total potential difference of the voltage supply is shared between the
components.
Cells in series
How can we find the potential
difference of several cells in series?
By adding the potential differences of each cell
The resistance rule for
components in series
For a series circuit made up several
components, how do we find the
total resistance of the components?
By adding the resistances of each component
Circuit rules
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Additional Science: Pages 218–219
Physics : Pages 160-161
Parallel circuits
Potential difference in a
parallel circuit
Calculations on parallel
circuits
P2 4.6 Parallel circuits
How could you calculate the total
current in a parallel circuit, if the
current through each of the
components is known?
By finding the sum of the currents through the separate components
What effect does increasing the
resistance of a component have on
the current through it?
The current through the component decreases.
What can we say about the potential
difference in a parallel circuit?
The potential difference across each component is the same.
What does the current through each
component in a parallel circuit
depend on?
The resistance of the component
Write down the equation used to
calculate the current, giving the
units.
Current (amperes) =
Calculate the current through a 6 Ω
resistor when a potential difference
of 12 V is applied to it.
Current = potential difference ÷ resistance
= 12 V / 6 Ω
=2A
The resistor is in a parallel circuit
with another, identical resistor.
Calculate the total current from the
battery if the potential difference
across each resistor is unchanged.
Total current = sum of current through each resistor = 2 A + 2 A = 4 A
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potential difference (volts)
resistance (ohms)
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Additional Science: Pages 222–223
Physics : Pages 164-165
P2 5.1 Alternating current
An swer s: 5. M ain s electr icit y
Alternating current
Mains circuits
Measuring an alternating
potential difference
More about mains circuits
What is meant by the term ‘direct
current’?
A current that is in one direction only
What is meant by the term
‘alternating current’?
A current that repeatedly reverses its direction
What is the mains frequency in the
UK?
50 cycles per second (50 Hz)
Name the two types of wire that
every mains circuit has.
1) Live wire
Which of these wires is dangerous
and why?
The live wire because it reaches voltages of over 300V.
Which device can we use to observe
alternating potential differences?
An oscilloscope
(HIGHER): How would you use an
oscilloscope to measure the
frequency of an alternating current?
By measuring the time period of the waves (the time taken for one cycle) and then
using the formula: frequency = 1/time taken for one cycle
The voltage of a mains live wire
alternates between 325 V and
-325 V. What direct voltage is this
equivalent to (in terms of electrical
power)?
230 V
(HIGHER): The frequency of the mains
supply is 50 Hz. What would the
frequency be if each cycle took 0.04
seconds instead of 0.02 seconds?
Learning Grids for GCSE AQA A Physics 2
Frequency
2) Neutral wire
= 1/time taken for one cycle
= 1/0.04 seconds
= 25 Hz
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Additional Science: Pages 224–225
Physics : Pages 166-167
P2 5.2 Cables and plugs
Why does an appliance with a metal
casing need to be earthed?
To stop the metal casing becoming ‘live’ if the live wire touches the case
Why are sockets and plug cases
made of plastic materials?
Because plastic materials are very good electrical insulators
Cables and plugs
Draw the double insulation symbol,
carried by appliances with plastic
casing.
Plugs, sockets and cables
What are the three pins of a threepin plug?
1) Live pin
Give three reasons for making the
pins out of brass.
Brass is a good electrical conductor, it does not rust and it is harder than copper
(does not bend easily).
What colour are the three wires in a
three-pin plug?
The live wire is brown, the neutral wire is blue, and the earth wire is striped green
and yellow.
What do mains cables consist of?
Two or three insulated copper wires encased by a layer of flexible plastic material.
Why are the cables that join wall
sockets on a house thicker than the
cables joining the light fittings?
Because more current passes through the socket cables than through the lighting
cables, and so the wires must be thicker to prevent them becoming too hot.
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2) Neutral pin
3) Earth pin
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Additional Science: Pages 226–227
Physics : Pages 168-169
Fuses
The importance of earthing
Circuit breakers
P2 5.3 Fuses
What is the purpose of a fuse?
A fuse contains a thin wire which heats up, melts and cuts off the current if the
current is too large.
What is the rating of a fuse?
The maximum current that can pass through the fuse without melting the fuse wire
What might happen if a fuse of the
wrong rating is fitted for a mains
appliance?
The fuse might blow, or it might let too much current through and cause a fire.
The earth connection of an
appliance with a metal casing is
broken. What else has to happen for
the appliance to become dangerous
to touch?
The live wire breaks and touches the metal case.
If the earth connection is mended,
why might the appliance still be
dangerous?
The increased current may cause the wires of the appliance to overheat.
Why don’t appliances with plastic
cases need to be earthed?
Because plastic is an insulator and so the case cannot become live
What is a circuit breaker?
An electromagnet switch that switches off (opens) when there is a fault
Give two advantages of using circuit
breakers over fuses.
1) They work faster than fuses.
2) They can be reset more quickly.
What does RCCB stand for?
Residual Current Circuit Breaker
When does an RCCB cut off the
current?
When the current in the live wire is different from the current in the neutral wire
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Additional Science: Pages 228–229
Physics : Pages 170-171
Electrical power and
potential difference
Calculating power
Choosing a fuse
P2 5.4 Electrical power and potential difference
Write down a word equation used to
find the power of an appliance from
the energy transferred by the
appliance. Include the units.
Power (watts) =
A microwave transfers 60,000 J over
100 s. Calculate its power.
Power = energy transferred ÷ time
= 60,000 J ÷ 100 s
= 600 W
Write down the equation used to
find the power supplied to an
appliance from the current and
potential difference. Include the
units.
Power supplied (watts) = current (amperes) × potential difference (volts)
Rewrite the equation using letters.
P=I×V
Calculate the power supplied to a
0.2 A, 2 V lamp.
P = I × V = 0.2 A × 2 V = 0.4 W
Write down the rearranged
equations used to find (1) potential
difference and (2) current.
1) V = P / I
energy transferred (joules)
time (seconds)
2) I = P / V
What are the three fuse ratings that
are commonly fitted within domestic 3 A, 5 A and 13 A.
electrical appliances?
Which of these fuses would you use
for a 920 W, 230 V appliance?
Learning Grids for GCSE AQA A Physics 2
Current = 920 W ÷ 230 V = 4 A
The current exceeds 3 A, and so a 5 A fuse should be used.
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Additional Science: Pages 230–231
Physics : Pages 172-173
Calculating charge
(HIGHER)
Energy and potential
difference
P2 5.5 Electrical energy and charge
What is the electric current through
an appliance?
The rate of flow of charge through the appliance
What is the unit of charge?
The coulomb (C)
Write down the equation used to
calculate the electric charge from
the current.
Charge = current × time
Rewrite the equation using the
letters ‘I’, ‘Q’ and ‘t’.
Q=I×t
Calculate the charge flow when the
current is 5 A for 1 minute.
1 minute = 60 seconds
Charge flow = current × time = 5 A × 60 s = 300 C
Why does a resistor heat up when
connected to a battery?
When the resistor is connected, electrons are pushed through the resistor by the
battery. As electrons repeatedly collide with the vibrating metal ions of the resistor,
they transfer kinetic energy to them, which makes them vibrate more. This causes
the resistor to heat up.
What two factors does the energy
transferred in a certain time in a
resistor depend on?
1) The amount of charge passing through the resistor
2) The potential difference across the resistor
Write down the equation used to
calculate the energy transferred
using these two factors, including
the units.
Energy transferred (joules) = potential difference (volts) × charge (coulombs)
Calculate the energy transferred to a
resistor when the charge passing
through it is 200 C and the potential
difference is 30 V.
Energy transferred = potential difference × charge
= 30 V × 200 C
= 6,000 J
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(HIGHER)
Energy transfer in a circuit
A circuit consists of a 6 V battery
connected to a resistor and a
filament bulb. What can you say
about the sum of electrical energy
transferred to the resistor and the
bulb?
The sum will equal the electrical energy supplied by the battery.
Each coulomb of charge leaves the
battery with 6 J of energy. If 4 J of
energy per coulomb is transferred to
the filament bulb, how much energy
per coulomb is transferred to the
resistor?
6 J = 4 J + energy transferred to the resistor per coulomb
Therefore energy transferred to the resistor per coulomb = 6 J - 4 J = 2 J per coulomb
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Additional Science: Pages 232–233
Physics : Pages 174-175
P2 5.6 Electrical issues (How Science Works)
Give two reasons why electrical
faults are dangerous.
Fault prevention
New bulbs for old
1) They can cause electric shocks, which can be fatal.
2) They can cause fires.
What causes electrical faults?
Damaged sockets, plugs, cables or appliances
How can electrical faults be
prevented?
By checking cables, plugs and sockets for damage regularly, and ensuring that
damages components are repaired or replaced by a qualified electrician
When would an electrician select a
two-core cable to use?
When fitting a wire to any ‘double-insulated’ appliance that doesn’t need to be
earthed
Why does an electrician have to take
the thickness of wires into account?
Electricians need to select wires of suitable thickness so that the heating effect of
the current through the wires is insignificant.
Give examples of two factors in
addition to cost that should be
considered when choosing an
electrical appliance.
1) The power rating
Name the two types of low-energy
light bulb.
2) The efficiency rating
1) Low-energy compact fluorescent lamp (CFL)
2) Low-energy light-emitting diode (LED)
Which of these bulbs are more
efficient?
LEDs
Which low-energy bulbs are typically
used for room lighting? Why might
they be chosen over the other type?
CFLs because they are significantly cheaper than LEDs (and more suited to room
lighting)
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Additional Science: Pages 236–237
Physics : Pages 178-179
P2 6.1 Observing nuclear radiation
An swer s: 6. R adio activit y
A key discovery
How did a packet of uranium salts
form the image of a key on the film
developed by Henri Becquerel?
The uranium salts sent out radiation. This passed around the key that was sitting on
top of the film, but it was blocked by the key.
What prize was Marie Curie awarded
for the discovery of polonium and
The 1911 Nobel Prize
radium?
Marie Curie
A radioactive puzzle
The origins of background
radiation
What is likely to have caused Marie
Curie to fall ill with leukaemia?
Radiation poisoning from the radioactive materials she worked with
Name a device which can be used to
detect radioactivity.
A Geiger counter
Name the three types of radiation
given out by radioactive substances.
In each case, give the symbol.
1) alpha radiation, α
Which type of radiation can be
stopped using a sheet of paper?
alpha radiation
Why do the unstable nuclei of
radioactive substances emit
radiation?
To become stable
What term is used to describe the
emission of radiation from an atom?
Radioactive decay
Why do we say that the emission of
radiation is a random event?
Because we can’t tell when an unstable nucleus will decay
Where can background radiation
come from?
The environment, from space or from devices such as X-ray machines
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2) beta radiation, β
3) gamma radiation, γ
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Additional Science: Pages 238–239
Physics : Pages 180-181
P2 6.2 The discovery of the nucleus
What famous discovery did Ernest
Rutherford make in 1913?
The discovery of the nucleus
What experiments did he use to
prove his discovery?
Alpha particle scattering experiments
How did Rutherford deduce that the
nuclei of atoms are positively
charged?
Because (positively charged) alpha particles were repelled by the nuclei, and like
charges repel, therefore the nuclei must be positively charged.
How did Rutherford deduce that the
The discovery of the nucleus atomic nucleus is much smaller than
the atom?
Because most alpha particles pass through the atom without deflection
1) It agreed with measurements that Geiger and Marsden had made in their
experiments.
Give three reasons why Rutherford’s
nuclear model was quickly accepted.
2) It explained radioactivity in terms of the changes that happen to an unstable
nucleus when radiation is emitted.
3) It predicted the existence of the neutron.
Goodbye to the plum
pudding model!
Describe the ‘plum pudding’ atomic
model.
Some scientists thought that the atom consisted of positively charged matter, evenly
spread out, with electrons buried inside, similar to plums in a plum pudding.
Why did Rutherford’s experiments
disprove the plum pudding model?
The plum pudding model couldn’t explain why some alpha particles were scattered
through large angles by atoms.
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Additional Science: Pages 240–241
Physics : Pages 182-183
Nuclear reactions
P2 6.3 Nuclear reactions
How is a charged particle formed?
A charged particle is formed when an atom loses or gains electrons.
What is a charged particle called?
An ion
What does the ‘atomic number’
refer to?
The number of protons in a nucleus
What symbol is the atomic number
given?
Z
What are isotopes?
Atoms of the same element with different numbers of neutrons.
What name is given to the number
of protons and neutrons in a
nucleus?
The mass number
mass number
Label the symbols on the diagram
(representing an isotope) with the
terms ‘atomic symbol’, ‘atomic
number’ and ‘mass number’.
Radioactive decay:
α emission
atomic number
A
Xxx
chemical symbol
Z
What does an alpha particle consist
of?
Two protons and two neutrons
Write down the symbol used to
represent the alpha particle.
4
2α
(HIGHER) What happens to the atomic
number and mass number of a
Its atomic number goes down by 2 and its mass number goes down by 4.
nucleus when it emits an alpha
particle?
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What happens in the nucleus when a A neutron in the nucleus changes into a proton and a β particle (electron). The β
beta particle is created?
particle is instantly emitted at high speed.
Write down (1) the relative mass and
1) Relative mass is effectively zero.
(2) the relative charge of a β particle.
β emission
Write down the symbol used to
represent the beta particle.
2) Relative charge is -1.
0
-1β
(HIGHER) What happens to the atomic
number and mass number of an
The atomic number goes up by 1, but the mass number stays the same.
unstable nucleus when it emits a β
particle?
γ emission
When does γ radiation take place in
the nucleus?
After an α or β particle has been emitted
What are the properties of γ
radiation?
γ radiation is uncharged and has no mass.
What happens to the number of
protons and neutrons in the nucleus
after γ radiation has been emitted?
They are unchanged.
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Additional Science: Pages 242–243
Physics : Pages 184-185
P2 6.4 More about alpha, beta and gamma radiation
Describe the two steps that should
be used to find the count rate due to
a radioactive source using a Geiger
counter.
1) Measure the background count rate.
How can we test the range of the
source in the air?
By moving the Geiger tube away from the source until the count rate due to the
source drops to zero.
Penetrating power
Fill in the table, giving the absorber
materials that can stop each type of
radiation and the thickness needed.
The nature of alpha, beta
and gamma radiation:
deflection by a magnetic
field
2) Measure the count rate with the source in place, and subtract the background
count rate from this to find the source count rate.
Radiation type
Absorber material
Thickness needed
alpha
sheet of paper
very thin
beta
metal sheet
a few mm
gamma
lead or concrete
several cm of lead, or
more than 1 m concrete
How does gamma radiation move
through air?
It spreads out without being absorbed.
What is a β particle?
A fast-moving electron
Why are α particles deflected in the
opposite direction to β particles?
Because α radiation consists of positively charged particles while β radiation consists
of negatively charged particles
Why are α particles harder to deflect
than β particles?
Because α particles have a much greater mass than β particles
What does gamma radiation consist
of?
Electromagnetic radiation
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alpha
gamma
The diagram show radiation passing
through an electric field. Label the
separated beams as ‘alpha’, ‘beta’
and ‘gamma’ radiation.
Deflection by an electric
field
Radioactivity dangers
beta
What other type of field could be
used to deflect radiation?
A magnetic field
When an alpha particle passes
through an electric field, what can
be said about the force deflecting it,
compared to a beta particle?
It is twice as great.
Why is this?
Because the charge of an alpha particle is twice that of a beta particle
What is ionisation?
Ionisation is when radiation from a radioactive substance knocks electrons out of
other atoms, causing them to become charged.
Why can ionisation be a danger
when radiation passes through a
living thing?
Ionisation in a living cell can damage or kill the cell. Damage to the genes inside a
cell can be passed on if the cell generates more cells.
Which type of radiation is more
dangerous in the body and why?
Alpha radiation because it has a greater ionising effect than beta or gamma
radiation
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Additional Science: Pages 244–245
Physics : Pages 186-187
Half-life
The random nature of
radioactive decay
P2 6.5 Half-life
What do we mean by the ‘activity’ of
a radioactive isotope?
The number of atoms that decay per second
How do we measure the count rate
due to a sample?
By using a Geiger counter to measure the number of counts per second
What can you say about the average
time taken for the count rate to fall
by a half?
It is always the same.
What do we mean by ‘half-life’?
The average time it takes for the number of nuclei of a radioactive isotope in a
sample to half
After one half-life, what will have
happened to the count rate?
It will have halved.
Why do we say that radioactivity is a
random process?
Because we can’t predict when an individual atom will decay
Why can we predict how many
atoms will decay in a certain time?
Because there are (usually) a very large number of atoms in a sample
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Additional Science: Pages 246–247
Physics : Pages 188-189
Automatic thickness
monitoring
Radioactive tracers
P2 6.6 Radioactivity at work
What two factors need to be considered
when choosing a radioactive substance
for a particular job?
1) The half-life of the substance
When is automatic thickness
monitoring used?
When making metal foil
How does an automatic thickness
monitor know when the foil is too thick?
The amount of β radiation penetrating the material drops and so the detector
reading drops.
What does the detector then do to
correct the thickness?
The detector sends a signal to the rollers, which then increase the pressure on the
sheet, making it thinner again.
What are radioactive tracers used for?
To track the flow of a radioactive substance though a system
Radioactive iodine is used as a
radioactive tracer in patients with
suspected blocked kidneys. Give three
reasons for choosing radioactive iodine.
2) The type of radiation given out
1) Its half-life is a few days, so it lasts long enough for the test to be done but
decays almost completely after a few weeks.
2) It decays into a stable product.
3) It emits gamma radiation, so it can be detected outside the body.
What are (1) carbon dating and (2)
uranium dating used for?
Radioactive dating
1) To find the age of ancient wood
2) To find the age of igneous rocks
Which has a longer half-life: radioactive
carbon or uranium?
Uranium
What is measured during carbon dating?
The count rate from the wood
What needs to be measured during
uranium dating?
The number of atoms of uranium and lead
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Additional Science: Pages 250-251
Physics: Pages 192–193
P2 7.1 Nuclear fission
An swer s: 7. Energ y from the nu cleu s
What happens to the nucleus of a
fissionable substance during the
process of nuclear fission?
The nucleus splits into two smaller ‘fragment’ nuclei.
What does the term ‘chain reaction’
refer to?
When a nuclear fission event causes other fissionable nuclei to split, which causes
yet more fission events, etc.
What are fission neutrons?
Neutrons that are released during nuclear fission
What two forms of energy are
released during nuclear fission?
1) Radiation (electromagnetic) radiation
In a nuclear fission reactor, what
ensures that energy is released at a
steady rate?
Even though there are several fission neutrons from each fission event, on average
only one neutron from each event will go on to produce further fission.
What fuel do most nuclear reactors
currently use?
Enriched uranium
Which uranium isotope is
fissionable?
Uranium-235
What percentage of natural uranium
is fissionable?
Less than 1%
Chain reactions
Fission neutrons
Fissionable isotopes
2) Kinetic energy
Give an example of a fissionable
isotope that U-238 nuclei can change Plutonium-239
into in a uranium reactor.
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Control rods
Fuel rods
Label the following diagram of a
reactor core.
Inside a reactor
Coolant
Why do the fission neutrons need to
be slowed in the reactor?
Because fast neutrons don’t cause further fission of U-235
What is the role of the control rods?
To absorb surplus neutrons to keep the chain reaction under control
Why is the reactor core made from
thick steel?
To withstand the high temperature and pressure in the core
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Additional Science: Pages 252-253
Physics: Pages 194–195
Fusion reactions
Fusion reactors
A promising future
P2 7.2 Nuclear fusion
What happens during nuclear
fusion?
Two small nuclei are fused together to form a single, larger nucleus, releasing
energy.
What does the core of the Sun
consist of?
A plasma of bare hydrogen and helium nuclei with no electrons
When do nuclei in the Sun fuse
together?
When they collide
What is formed when two protons
fuse together?
A heavy hydrogen nucleus
What happens to the energy
released at each stage of nuclear
fusion in the Sun?
It is carried away as kinetic energy of the product nucleus and other emitted
particles.
Why will two nuclei approaching
each other repel each other?
Because they are both positively charged
How can this repulsion be
overcome?
By getting the nuclei to move fast enough towards each other
When did scientists start working on
building a successful nuclear
reactor?
In the 1950s
Why are fusion reactors an
important area of research?
Because practical fusion reactors could meet all our energy needs
Give two advantages that nuclear
fusion has over nuclear fission for
generating electricity.
Learning Grids for GCSE AQA A Physics 2
1) Fuel (heavy hydrogen) is readily available.
2) The reaction product is helium, which is harmless compared to nuclear waste.
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Additional Science: Pages 254-255
Physics: Pages 196–197
Radioactivity all around us
Chernobyl
P2 7.3 Nuclear issues (How Science Works)
On average, what radiation dose
does a person in the UK get each
year as a result of nuclear weapons
testing?
5 units/year
What about from natural
radioactivity in the air?
1,190 units/year
Why do the medical sources of
radiation include X-rays?
Because X-rays have an ionising effect
Where has the radon gas in the air
come from?
It has seeped up through the ground from radioactive substances deep
underground.
Why is radon gas dangerous?
It emits alpha particles which are hazardous to people’s health if breathed in.
Where are used fuel rods from
nuclear reactors stored after
removal?
In large water tanks for up to a year
What happens to the waste after it
has been cooled?
It is stored securely for many years after unused uranium and plutonium have been
removed.
When did the Chernobyl accident
happen?
In 1986
Describe how the accident could
have been avoided.
By installing high-speed shutdown systems, following safety regulations and using a
better reactor design.
How many nuclear reactors are now
in operation around the world?
Thousands
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What type of radiation is the most
dangerous if it gets inside the body?
Alpha radiation
1) Keep as far as possible from sources of radiation.
Radioactive risks
Give three ways that workers at risk
from ionising radiation can minimise
their exposure to the radiation.
2) Spend as little time as possible inside ‘at risk’ areas.
3) Use radiation shields or stay behind thick concrete barriers.
What are the new reactors called
that will replace most of the world’s
nuclear reactors over the next
20 years?
Learning Grids for GCSE AQA A Physics 2
Third-generation nuclear reactors
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Additional Science: Pages 256-257
Physics: Pages 198–199
The early universe
The Dark Age of the
universe
The force of gravity takes
over
P2 7.4 The early universe (How Science Works)
What was created in the Big Bang?
The universe, including space, time and radiation
What happened to the universe as it
expanded?
It cooled down.
Which two particles were formed
when the universe was only
100 seconds old?
Neutrons and protons
Which galaxy do the stars we see in
the night sky belong to?
The Milky Way galaxy
How many galaxies are in the
universe?
Billions
What was the universe like during its
‘Dark Age’?
It was a completely dark, patchy cloud of hydrogen and helium.
Which bodies formed to end the
Dark Age of the universe?
Stars and galaxies
How did the force of gravity end the
Dark Age of the universe?
Gravity pulled matter together to form dense clumps, which eventually turned into
stars and galaxies.
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Additional Science: Pages 258-259
Physics: Pages 200–201
The birth of a star
Shining stars
The end of a star
What remains after a
supernova occurs?
P2 7.5 The life history of a star
What are stars formed from?
Clouds of gas and dust
What is a protostar?
A concentrated cloud that can go on to form a star
What happens when the protostar
heats up?
The nuclei of light elements fuse together and energy is released, causing the core to
get hotter and hotter, eventually forming a star.
What are main sequence stars?
Stars that are in the main stage of their life
Which two forces have to be
balanced for a star to be stable?
1) Force of gravity (inwards)
When will these forces cease to be
balanced?
When most of the hydrogen nuclei in the core have been fused together.
What are the stages in the life of a
low-mass star?
Protostar  main sequence star  red giant  white dwarf black dwarf
What type of star will the Sun
eventually become?
A black dwarf
What happens during the collapse of
a red supergiant?
Matter surrounding the star’s core compresses the ore more and more, until the star
explodes in a supernova explosion.
What happens to the core of a highmass star after a supernova occurs?
It is compressed into a neutron star.
What is formed if the star is massive
enough?
A black hole
Why is a black hole black?
Because the gravitational field of a black hole is so strong that not even light can
escape from it
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2) Force of radiation (outwards)
© ZigZag Education 2011-12
Additional Science: Pages 260-261
Physics: Pages 202–203
The birthplace of the
chemical elements
Planet Earth
P2 7.6 How the chemical elements formed
How are light chemical elements
formed in stars?
During fusion reactions
What is the heaviest element that
can be formed during fusion?
Iron
What does the debris from a
supernova contain?
All the known elements
What will eventually happen to the
debris?
It will be pulled together to form new stars and planets.
What is the heaviest known natural
element?
Uranium
What does the presence of this
element on the Earth suggest?
That the Solar System formed from the debris of a supernova
How can scientists make elements
that are heavier than uranium?
By bombarding heavy elements with high-speed neutrons
Why aren’t heavier elements such as
plutonium naturally present on the
Earth?
Because they would have decayed after the supernova, before the formation of the
Earth
Learning Grids for GCSE AQA A Physics 2
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© ZigZag Education 2011-12