Electromagnetism

A coil of wire acts like a when an electric current flows through it.  One end becomes a north-seeking pole and the other end a .  This is called an .

The strength of the field can be increased by:

• by placing an inside the coil
• by increasing the number of on the coil
• by increasing the size of the flowing through the coil

Reversing the current in an electromagnet reverses the of the electromagnet.

The motor effect

When a wire carrying an electric current is placed in a magnetic field, it may experience a force. The size of the force can be increased by:

• the strength of the magnetic field
• the size of the current.

The direction of the force is reversed if either the direction of the or the direction of the is reversed.

 Uses of Electromagnetism

## Dumping cars!

A huge electromagnet is often used to pick up cars.  When the current is switched off, the magnet its magnetism and the car falls back down to the ground.

## Electric motors

An electric motor uses the motor effect to a coil of wire inside a magnetic field.

List three ways you can increase the speed of a motor: