2021 Past Paper (Higher)

Question 1

Which equation links energy transferred (E), power (P) and time (t)?

Answer 1

energy transferred = power × time

Question 2

Which equation links current (I), potential difference (V) and resistance (R)?

Answer 2

V = I × R

Question 3

Nuclear fusion is the joining together of________
During nuclear fusion the total mass of the particles________

Answer 3

nuclei
decreases

Question 4

The idea of obtaining power from nuclear fusion was investigated using models. box
The models were tested before starting to build the first commercial nuclear fusion
power station.
Suggest two reasons why models were tested.

Answer 4

• to make sure the fusion
  process is possible
• to develop an understanding
  of the process
• to make adaptations to the
  process
• to assess the efficiency of the
  process
• to make predictions
• assess safety risks
• to assess environmental
  impact
• set-up cost is lower (for small
  scale experiments)

Question 5

Explain one environmental effect of generating electricity using fossil fuels.
[2]

Answer 5

releases carbon dioxide
which causes global warming
OR
releases particulates
which causes global dimming
OR
releases sulfur dioxide
which causes acid rain

Question 6

Student A investigated how the current in resistor R at constant temperature varied
with the potential difference across the resistor.
Describe a method that Student A could use for this investigation.

Answer 6

• measure the current in R using the ammeter
• measure the p.d. across R using the voltmeter
• vary the resistance of the variable resistor
  (or vary the number of cells or use a variable power supply)
• record a range of values of current and p.d.
• ensure current is low to avoid temperature increase
• switch circuit off between readings
• reverse connection of R to power supply
• repeat measurements of I and V in negative direction
• plot a graph of current against p.d.

Question 7

Explain how the increased temperature of resistor R would have affected
Student results.

Answer 7

current and p.d. would not be directly proportional
(because) resistance of R would increase

Question 8

The digital ammeter has a higher resolution than the moving coil ammeter.
Give one other reason why it would have been better to use a digital ammeter
throughout an investigation.

Answer 8

• less chance of misreading
• no parallax error
• it can give a reading closer to
  the true value

Question 9

The student determined the volume of each fruit using a displacement can and a
measuring cylinder.
What other piece of equipment would the student need to determine the density of
each fruit?

Answer 9

balance / scales

Question 10

Write down the equation which links density (ρ), mass (m) and volume (V). box

Answer 10

density = mass/
volume

Question 11

The student only measured the volume of each fruit once.
The volume measurements cannot be used to show that the method to measure
volume gives precise readings.
Give the reason why

Answer 11

repeat readings (of volume)
need taking (of each fruit) to
show that the readings are close
together

Question 12

It is unlikely that all of the electricity that the UK needs can be generated by solar
power systems.
Explain why

Answer 12

a really large area of land would need to be covered with solar cells

due to the low useful power output of the solar cells

Question 13

What is meant by the ‘random nature of radioactive decay’?

Answer 13

can’t predict which nucleus will decay next

Question 14

A polonium (Po) nucleus decays by emitting an alpha particle and forming a box
lead (Pb) nucleus.
The lead (Pb) nucleus then decays by emitting a beta particle and forms a bismuth (Bi) nucleus.
The bismuth (Bi) nucleus then decays by emitting a beta particle and forms a
polonium (Po) nucleus.
Explain how these three decays result in a nucleus of the original element, polonium.

Answer 14

one alpha decay would
decrease proton number by 2
two beta decays would increase
proton number by 2
so the proton / atomic number of
the final nucleus is the same as
the proton / atomic number of
the original nucleus

Question 15

Explain how closing the switch would affect the current in the variable resistor in a parallel cicuit

Answer 15

current would be (almost) zero
(in the variable resistor)
(because) the switch has
(effectively) zero resistance

Question 16

what can be considered a closed system of a and b

Answer 16

The total energy of a and b is constant

Question 17

At position C the car’s gravitational potential energy is 0.20 J greater than at
position B.
How much kinetic energy does the car need at position B to complete the loop of
the track?

Answer 17

more than 0.20 J
(because) the car needs to be
moving at the top of the loop

Question 18

When the volume of gas in the syringe increased, the pressure on the inside walls of the syringe decreased.
Explain why

Answer 18

there are less frequent collisions
between the particles and the walls of the syringe

(causing) a lower (average)
force on the walls of the syringe

(and) pressure is the total force per unit area

Question 19

Explain the advantage of transmitting electricity at a very high potential difference.

Answer 19

very low currents

which means less (thermal)
energy is transferred to
surroundings

which increases the efficiency of
power transmission

Question 20

While flying a kite, The person could receive a fatal electric shock if the kite was very close to, but not touching the power cable.
Explain why

Answer 20

electric field strength is very
high

causing the air to become
ionised

(the kite / string) conducts
charge to the person / earth

Question 21

A 1 metre length of a single aluminium wire is a better conductor than a 1 metre
length of the steel wire.
The individual wires behave as if they are resistors connected in parallel.
Explain why the current in the steel wire is different to the current in a single
aluminium wire.

Answer 21

the potential difference across
the wires/cable is the same
(but) the resistance of the steel
wire is greater (and so less
current in the steel)

Question 22

The specific heat capacity of ice is less than the specific heat capacity of water.
Explain how Figure 17 shows this.

Answer 22

the gradient for ice is steeper
than the gradient for water
(liquid)
which means that less energy is
needed to increase the
temperature by a fixed amount

Question 23

The specific latent heat of fusion of ice is less than the specific latent heat of box
vaporisation of water.
Explain how Figure 17 shows this.

Answer 23

water took more time to
vaporise than the ice took to
melt
which means that less energy is
needed to change the state from
solid to liquid (than from liquid to
vapour)

Question 24

In the second student’s investigation of specific latent heat, more thermal energy was transferred to
the surroundings.
Describe two ways the results of the experiment in a diagram would have been
different.

Answer 24

• ice/water would take more
  time to increase in
  temperature
• ice/water would take more
  time to change state
• the change in temperature
  with time would not be linear