Magnets

A magnet can exert a force on another nearby magnet. Magnets have two poles:

The magnetic force is strongest near the magnet's poles.

A bar magnet, with the north and south poles marked red and blue.

The rules of magnetism

Two magnets will either attract or repel each other in the following way:

  • like poles (N–N or S–S) repel
  • unlike poles (N–S or S–N) attract

Magnetic forces are non-contact forces – this means that magnets affect each other without touching.

Induced and permanent magnetism

Iron, steel, nickel and cobalt are magnetic materials. They are affected by magnets and are attracted to either pole of a magnet.

Permanent magnets

A permanent magnet is often made from a magnetic material such as iron. A permanent magnet always causes a force on other magnets, or on magnetic materials. Key features of a permanent magnet:

  • it produces its own magnetic field
  • the magnetic field cannot be turned on and off – it is there all the time

Bar magnets and horseshoe magnets are examples of permanent magnets.

Induced magnets

Unlike a permanent magnet, an induced magnet only becomes a magnet when it is placed in a magnetic field. The induced magnetism is quickly lost when the magnet is removed from the magnetic field.

Like all induced magnets:

  • they are only attracted by other magnets, they are not repelled
  • they lose most or all of their magnetism when they are removed from the magnetic field