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:

 

Press the button to check your answers:

 

Click to go to next page on motors

 

 

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