Electricity and magnetism

Question 1

Define and give examples of static electricity.

2 marks

Answer 1

Static electricity is the build-up of electrons in one place. Examples include lightning and when you rub a balloon against your hair.

Question 2

Define current electricity.

1 mark

Answer 2

Current electricity is electricity flowing around a circuit.

Question 3

The flow of conventional current is 1)………. to the flow of electrons. Electrons flow 2)………. to 3)……….

3 marks

Answer 3

1. Opposite
2. Negative
3. Positive

Question 4

Distinguish between an electrical conductor and an electrical insulator.

2 marks

Answer 4

A conductor allows electricity to flow through it, whereas an insulator doesn’t.

Question 5

Define voltage and state its units.

2 marks

Answer 5

The voltage, also known as potential difference, of a supply is a measure of the energy given to the electrons in a circuit. It is the voltage between two points that makes an electric current flow between them. Voltage is measured in volts (V).

Question 6

Define current and state its units.

2 marks

Answer 6

Current is how much electricity is flowing through a point in a circuit. It is measured in amperes or amps (A).

Question 7

Define resistance and state its units.

2 marks

Answer 7

Resistance is the opposition in an electrical component to the current flowing through it. It is measured in ohms (Ω).

Question 8

Define an LDR and how it works.

2 marks

Answer 8

An LDR is a component with a resistance that depends on light intensity. Usually the resistance is low in bright light and high in the dark.

Question 9

Define an LED and how it works.

2 marks

Answer 9

A light-emitting diode is a compact light source which only allows current to flow through it in one direction. It emits light when a small current flows through it.

Question 10

Describe some common properties of magnets.

3 marks

Answer 10

1. They have a north pole (N) and a south pole (S).
2. They attract the metals iron, cobalt and nickel.
3. Their magnetic field gets weaker the further away you go from it.

Question 11

Describe how to make an electromagnet and how to make it stronger.

4 marks

Answer 11

To make an electromagnet, coil a copper wire and run current through it. It can be made stronger by increasing the amount of current flowing through it, adding more coils or inserting an iron core inside the coils.

Question 12

List some common uses of electromagnets.

6 marks

Answer 12

1. Electric bells
2. Relays in circuits
3. Sorting through metals in scrapyards
4. MRI scanners
5. Maglev trains
6. Reed switches in electronic circuits