Electromagnets and motors in action

Electricity and magnetism are closely linked. That link runs every electric motor in your home.

Practise this lesson free (7 questions)

Fields from currents

A current in a straight wire makes a magnetic field in circles around the wire. A compass placed nearby shows it. Reverse the current, and the field reverses.
Wind the wire into a coil (a solenoid) and the field looks like the field of a bar magnet, with a north and a south pole at the ends.
Unlike a permanent magnet, an electromagnet can be switched on and off and made stronger or weaker.

Investigating strength

Count how many paper clips an electromagnet can pick up.
Independent variable: number of turns (or the current). Dependent variable: number of clips. Control: same core, same current (or same turns), same clips.
More turns, a bigger current or an iron core make it stronger.
Example results with the current kept the same.
Number of turnsPaper clips picked up
103
206
309
4012

Motors and uses

In a DC motor, a coil carrying a current sits between the poles of a magnet. The magnetic forces push one side of the coil up and the other down, so it turns.
To make it spin faster: more current, more turns on the coil, or a stronger magnet.
To reverse it: reverse the current, or swap the magnet's poles.
Electromagnets are used in scrapyard cranes, electric door locks and electric bells; motors are in fans, drills and washing machines.
Worked example

Using the table, predict how many paper clips the electromagnet would pick up with 50 turns.

  1. Each extra 10 turns picks up 3 more clips.
  2. From 40 turns (12 clips), add 3 more.

Answer: 15 paper clips

Key idea

A current makes a magnetic field; a coil makes a field like a bar magnet. More turns, more current or an iron core make an electromagnet stronger. A motor spins faster with more current, more turns or a stronger magnet, and reverses if the current reverses.

Key words
Current
The flow of electric charge round a circuit, measured in amperes (A).
Electromagnet
A coil of wire carrying a current, which makes a magnetic field that can be switched off.
Independent variable
The variable you choose to change in an investigation.
Dependent variable
The variable you measure in an investigation.

All KS3 Science key terms and definitions →

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Extra practice

2 more questions

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  1. How could you show the magnetic field around a current-carrying wire?

    1. Place small compasses around the wire
    2. Use a thermometer
    3. Use a light meter
    4. Weigh the wire
    Show the answer

    Answer: Place small compasses around the wire

    Compasses line up with the field.

  2. What happens to the field of a coil when an iron core is added?

    1. It becomes stronger
    2. It changes to circles only
    3. It disappears
    4. It becomes weaker
    Show the answer

    Answer: It becomes stronger

    Iron concentrates the field.

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Sources and references

Checked by the GCSE-ready editorial team, 17 October 2026. Last updated 2 October 2026. Spotted a mistake? Tell us and we will fix it.