### KS3 Physics

Energy
Motion and Forces
Waves
Electricity and Electromagnetism
Matter
Space Physics

# Electromagnets

A magnetic field is created when an electric current flows through a wire. This can be used to create an electromagnet. The diagram below shows a simple electromagnet, consisting of a coil wrapped around an iron nail.

The word electromagnet can be split into two parts. ‘Electro‘ relates to electricity and ‘magnet‘ relates to magnetism. An electromagnet is a temporary magnet that produces a magnetic field when an electric current passes through a coil. The magnetic field will disappear when the current stops.

If the current is flowing upwards in the wire, as indicated by the red arrows, it will produce a circular magnetic field around the wire.

The arrows in the diagram above show the direction of the magnetic field. However, rather than being a straight wire, in an electromagnet, the wire is coiled.

When current flows through the coil of wire, the resulting magnetic field looks similar to the magnetic field of a bar magnet.

In this example, the coil of wire produces a magnetic field that flows out from the north pole and into the south pole.

The two open ends of the coil are attached to a power supply. Once you turn on the power supply and current is flowing through the wire, a magnetic field will be produced. When you turn off the power supply, the electromagnet loses its magnetism. This makes it useful for moving magnetic objects by picking them up and dropping them off in different places.

## Making Electromagnets Stronger

You might want to make the electromagnet stronger, and you can do so in three different ways:

1. Wrapping the coil around an iron core

2. Increasing the current flowing through the coil

• To increase the current flow, you can increase the potential difference using your power supply

3. Increasing the number of turns of the coil

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