Electromagnets

A coil with an iron core is called an electromagnet.

The iron core increases the coil’s magnetic field strength.

A simple electromagnet is made by coiling wire around an iron nail.

A coil of insulated wire is wrapped around an iron nail. One end of the coil of wire is connected to a battery. The other is connected to a switch in the circuitA simple electromagnet

Key points

Iron is easily magnetised and demagnetised.

Steel is more difficult to magnetise and is not easily demagnetised.

An iron core makes a temporary electromagnet.

It loses its magnetism as soon as the switch is opened and the current is switched off.

A steel core makes a more permanent magnet.

It does not lose its magnetism quickly when the current is switched off.

Electromagnets with iron cores are used:

  • in scrap yards to lift magnetic materials such as iron and steel;
  • to separate magnetic materials such as iron and steel from non-magnetic materials;
  • in electric bells;
  • in relay switches and door locks that can be controlled remotely;
  • to hold open fire doors – the electromagnet switches off when a fire alarm is sounded and the doors close.