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:
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 direction of the force is reversed if either the direction of the or the direction of the is reversed.
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.
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:
Press the button to check your answers:
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