# Induced potential and the generator effect

A or is needed to cause an electric current flow in a circuit.

## Inducing a potential difference

A potential difference can be induced (created) in a when there is movement between the conductor and a magnetic field. This can occur in two different ways:

• the conductor, normally a coil of wire, is moved in a magnetic field
• a magnet is moved near to the conductor or into the coil

This is called and is often referred to as the .

The induced potential difference produces an induced current if the conductor is connected in a complete circuit. As with all currents, the induced current creates a magnetic field around itself.

It is important to remember that if a magnet is moved into a coil of wire, the induced magnetic field tends to repel the magnet back out of the coil. This effect occurs whether a magnet is moved into a coil, or a coil is moved around a magnet.

## Factors affecting the induced potential

The direction of the induced potential difference or induced current depends on the direction of movement. The current is reversed when:

• the magnet is moved out of the coil
• the other pole of the magnet is moved into the coil

This image illustrate how this works.

An induced potential difference or induced current will increase if:

• the speed of movement is increased
• the magnetic field strength is increased
• the number of turns on the coil is increased

The invention of the electricity generator