Summer Revision 2020 Past Paper

Question 1

What is the potential difference and frequency of mains electricity in the UK?

Answer 1

230 V and 50 Hertz.

Question 2

What are the functions of an earth wire?

Answer 2

A safety wire to stop the case from becoming live.

Question 3

What are the functions of the live wire?

Answer 3

Carries the current.

Question 4

What are the functions of a neutral wire?

Answer 4

Completes the circuit.

Question 5

Why should a person not touch an unconnected metal case?

Answer 5

They person could get an electric shock because there is a current in the person.

Question 6

Why can a person touch a connected metal case?

Answer 6

The charge flows through the earth wire instead of the person,
because the resistance of the earth wire is much less than a person’s.

Question 7

What happens if you touch a live wire?

Answer 7

Will cause a large potential difference across the body. A current will flow through the body.

Question 8

For a thermistor, as temperature increases, resistance ___________.

Answer 8

decreases

Question 9

What happens to sub-atomic particles in the nucleus in alpha decay?

Answer 9

The nucleus emits two protons and two neutrons.

Question 10

What happens to sub-atomic particles in beta decay?

Answer 10

A proton is gained, but emits an electron.

Question 11

What happens in gamma decay?

Answer 11

Both mass and atomic number do not change at all.

Question 12

What are the differences in penetration for alpha, beta and gamma radiation?

Answer 12

Alpha radiation is the least penetrating. It can be stopped by a sheet of paper.
Beta radiation has a stronger penetration, but can be stopped by a thin aluminium sheet.
Gamma radiation is the most penetrating, it can only be stopped by thick lead.

Question 13

Which type of radiation is the least ionising?

Answer 13

Gamma rays.

Question 14

What is a gamma ray?

Answer 14

A gamma ray is when the nucleus tries to cool down, it will emit an electromagnetic wave.

Question 15

Why did the student adjust the variable resistor every time the length of wire changed?

Answer 15

Because the variable resistor changes the resistance of the circuit.
So the current doesn’t change, so the temperature of the wire is constant.

Question 16

What is the relationship between the length and resistance of a wire?

Answer 16

Directly proportional.

Question 17

What is the equation for current?

And what is the unit for current?

Answer 17

current= potential difference/ resistance

Current is measured in Amps.

Question 18

How does heat change different energy stores as water is heated?
Wood-
Pipe-
Water-

Answer 18

Wood- Chemical energy decreases.
Pipe- Thermal energy increases.
Water- Thermal energy increases.

Question 19

Why does the temperature of water stay constant while burning? (2)

Answer 19

The heat energy is used to change the state of water from a liquid to gaseous water vapour.
The energy is also dissipated to surroundings.

Question 20

Why is the thermal conductivity of metal important for bowl design?

Answer 20

Metal has a high thermal conductivity, so it increases the rate of energy transfer from the mixture towards the coolant.

Question 21

Why is the thermal conductivity of plastic important for bowl design?

Answer 21

Plastic has a low thermal energy, so it slows down the rate of energy transfer from the outside to the coolant.

Question 22

What is the definition of specific latent heat?

Answer 22

The amount of energy needed to change the state of 1kg of a substance without changing temperature.

Question 23

Why are dice used to model radioactive decay and half-life?

Answer 23

Both are rolled at random processes.

Question 24

Why can a kangaroo jump higher as their speed increases? (3)

Answer 24

Because the tendons stretch more,
increasing its elastic potential energy.
This is transferred to surroundings as gravitational potential energy.