Electromagnets

A magnetic field exists around all wires carrying a current.

Magnetic field around a wire

A current continues travelling down the wire. The bottom left meter points downwards A current travels down the wire producing a circular magnetic field. Compasses around the wire allign with the magnetic field.

When there is no current the compass needles in the diagram line up with the Earth's magnetic field. A current through the wire produces a circular magnetic field.

The magnetic field for a coil of wire is shown below. The magnetic fields from each of the turns in the coil add together, so the total magnetic field is much stronger. This produces a field which is similar to that of a bar magnet. A coil of wire like this is often called a solenoid.

Coil of wire showing magnetic field, which is stronger closer to the coil.Coil of wire showing magnetic field, which is stronger closer to the coil.