What Causes The Motor Effect?

The motor effect is the movement caused by a combination of electricity and magnetism. It occurs when a temporary electromagnet is brought near to a permanent magnet and the two magnetic fields interact. When there is no current in the conducting wire of an electromagnet, the magnetic field of the permanent magnet will go straight across between the poles of the magnet.

When a current flows through the conducting wire, it produces a circular magnetic field. Below the wire, the magnetic field due to the current in the wire is in the same direction as the field from the magnet, but above the wire the magnetic field due to the current is in the opposite direction to the field from the magnet. This means the field is stronger below the wire but weaker above it. The wire is pushed upwards by the stronger field below, and this is how movement occurs, caused by the motor effect.