The Only Honest Test

Hold a magnet near a steel paperclip and it leaps across the gap and sticks. Hold it near an aluminium spoon and nothing happens at all — even though both are metal, both are shiny, both feel much the same in your hand.

So a magnet is fussy. It doesn't grab everything, and it doesn't even grab every metal.

Now try something better. Take two magnets and bring them together end to end. Sometimes they snap together so hard you can hear it. Turn one of them round and try again, and now they refuse — they push each other apart, and if you hold them close you can feel the shove, an invisible hand between your fingers.

That pushing is the important half, and here's why. A magnet pulls in a nail, and a nail pulls in a magnet. Attraction happens both ways, so seeing something get pulled towards a magnet tells you almost nothing about what it is. But being pushed away — that only ever happens between two magnets.

This lesson is really about a question a scientist asks constantly: which test would actually tell the two cases apart?

By the end of it you'll be able to:

• name the poles of a magnet and state the rule for which ends pull and which push
• say which materials a magnet works on, and which metals it ignores
• explain why attraction is not proof that something is a magnet, and repulsion is
• explain how a compass works, and what it is really pointing at