Electromagnetic induction

A magnet and a coil of wire can be used to produce an electric current. A voltage is produced when a magnet moves into a coil of wire. This process is called electromagnetic induction. The direction of the induced voltage is reversed when the magnet is moved out of the coil again. It can also be reversed if the other pole of the magnet is moved into the coil.

If the coil is part of a complete circuit, then a current will be induced in the circuit.

Notice that no voltage is induced when the magnet is not moving, even if it is inside the coil.

To increase the induced voltage:

  • move the magnet faster
  • add more turns to the coil
  • increase the strength of the magnet
Diagram showing a bar magnet outside a wire coil connected to an ammeter. There is no current.

1. A bar magnet rests outside a wire coil connected to an ammeter showing no current