The big idea
A magnet can pull on some things without even touching them. It can lift a paper clip, hold a drawing on the fridge, and point the way north in a compass.
How it works
Magnets pull on things made of iron or steel, like paper clips and nails. They do not pull on plastic, wood, glass or paper. They don't pull on most other metals either, such as the aluminium in a drink can.
Every magnet has two ends, called poles. One is the north pole and one is the south pole.
- A north pole and a south pole pull together. We say they attract.
- Two north poles push apart. So do two south poles. We say they repel.
All around a magnet is an invisible area where it can push and pull. This is its magnetic field. The field is strongest near the poles. It can even reach through paper, water and your hand.
A compass needle is a tiny magnet that can spin. The whole Earth acts like a giant magnet, so the needle turns until it lines up with the Earth. One end points north.
How it's made
Fridge magnets are made from a fine magnet powder mixed into a bendy, rubbery plastic. A machine rolls it flat, like rolling out pastry. Then the sheet is passed by a strong magnet, which turns it into a magnet too.
Super-strong magnets are made from metal powders. The powder is squashed into a block and baked in a very hot oven until it sticks together. At first the block is not magnetic at all! At the very end, a machine gives it a huge, quick zap of magnetism. Now it is a powerful magnet.
Try this!
You need a fridge magnet or bar magnet and some everyday things.
- Guess which things the magnet will pick up: a paper clip, a pencil, a spoon, a coin, a foil wrapper, a key.
- Test each one. Were your guesses right?
- Put a paper clip on top of a book and move the magnet under the book. Can the magnet pull through it?
Keep magnets away from phones, bank cards and small children, who might swallow them.
Wow!
Some birds and sea turtles can feel the Earth's magnetic field. They may use it like a map to find their way across the world.