Magnets everywhere(Introduction)

Finding magnets

Stop for a moment and think of all of the places where magnets are used in your home. There's the magnetic catches on the kitchen cupboards; the magnetic strip to hold the kitchen knives; all of that stuff stuck on the fridge door; some of the children's games work by magnets; electric motors have magnets inside them and isn't there something about not putting computer discs too close to magnets?

In fact you don't need to look too far at all to find magnets in use, but how do they work? If you stop and think for a moment it's a little strange that the magnetic shape will stick at all to the fridge door. How does that work? Normally we need some kind of adhesive to make things stick, but this is not the case with magnets. How come the magnet will stick to the fridge door but not to the stainless steel kitchen sink (try it!)? Is it possible to make a magnet? Are there simple rules that allow us to predict that the magnet will stick to the fridge but not to the sink?

There are lots of questions to be asked about magnets and children are often very keen to ask them.

Magnetic and non-magnetic materials

Fridge magnets will stick to some surfaces but not to others. It depends on what material the surface is made from. This makes for a simple categorisation: some materials are magnetic and some are not.

Magnetic materials are those which stick to, or are attracted to, magnets. The most common magnetic materials are iron-based (with other elements added to make iron alloys), along with cobalt and nickel.

Non-magnetic materials are those which do not stick to, or are not attracted to, magnets. Common non-magnetic materials include, wood, glass, PVC, aluminium, stainless steel.

All materials are magnetic

Although this simple classification of magnetic and non-magnetic materials is useful, you should bear in mind that all materials are magnetic in that they are affected, to a greater or lesser extent, by a magnetic field.

For example, it is possible to levitate water using a strong magnet.