Magnets attract some metals, such as iron, nickel, cobalt, and some alloys. You can magnetise a piece of one of these metals by stroking it with a magnet.

Sprinkle some iron filings onto a piece of paper on top of a magnet. You'll see them arrange into lines travelling from one end of the magnet to the other. Where they meet the magnet are the 2 'poles', one is called North, and the other, South.

A magnet is surrounded by an invisible force field. Electric coils, currents in wires, and permanent magnets are all sources of magnetic field. Magnetic fields are produced by moving charged particles: in electromagnets, electrons flow through a coil of wire connected to a battery; in permanent magnets, spinning electrons within the atoms generate the field. Lines of magnetic force can be seen around a magnet by sprinkling iron filings on to a sheet above it and tapping the sheet. The strength of the magnetic force is strongest close to the poles and gets weaker as you move away from the poles.

In the atoms of magnetic metals, the electrons spinning around the nucleus create a small magnetic field. Normally the electrons are paired and their fields cancel; but in iron, some of the electrons are unpaired. Their spins tend to line up together, creating tiny 'pockets' of magnetism called magnetic domains.

In an unmagnetised piece of iron, these domains fields point in different directions. If you magnetise the iron, the domains line up in the same direction, creating a larger magnetic field.