A magnetic field is created when an electric current flows in a wire. This can be used to create an electromagnet. The diagram below shows a simple electromagnet, with 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, going in the direction of the red arrows, this will produce a magnetic field around the wire that goes in circles.
The arrows in the diagram above show the direction of the magnetic field. But instead of a straight line, it would be a coil of wire.
When current is flowing through the coil of wire, the magnetic field will look similar to the magnetic field of a bar magnet.
Here we have a coil of wire, producing a magnetic field that flows out of the north pole and into the south pole.
The two open ends of the coil will be 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 an electromagnet, it loses its magnetism. This makes it useful for moving magnetic objects by picking them up and dropping them off in different places.
We may want to make the electromagnet stronger and we can do this in three different ways:
1. Wrapping the coil around an iron core
2. Increasing the current flowing through the coil
3. Increasing the number of turns of the coil