Science Questions

What are magnets made out of and why are they made? Andrew in Essex

Magnets are very useful things: you can stick things to fridges with them and they're very important in things like hard disk drives in your computer. You can even make levitating trains with them. But how do you make a magnet? Inside a metal like iron there are lots of tiny little magnets, but to start off with they're all pointing in different directions. It's like if you had a load of magnets inside a big bucket: they'd all be pointing in a random way. What you need to do to make it into a magnet is to line up all those tiny magnets. The way you do it is to heat up the material, which allows all the mini magnets to move around. You then put a big electric field around it. This causes all the little magnets to line up, as you may have seen compasses do in a magnetic field. If you then cool it down in that magnetic field they'll all be lined up and you'll have what you think of as a magnet. Of the elements in the periodic table iron, nickel and colbolt can be made into magnets. But you can also make alloys that make much stronger magnets. To make a very strong magnet you need something that will make the tiny magnets stay in the right orientation after it's been cooled.

October 2006