Question: How do you make a magnet?

Susan Cartwright answered on 19 Jun 2015:

First, take a piece of an appropriate material. Not many materials are ferromagnetic (that’s the type of magnetism that you need for a magnet): the main ones are iron, cobalt and nickel, though there are some more complicated ones like CrO2 (chromium dioxide).

Next, take an existing magnet, and stroke your piece of iron, cobalt or nickel along its length. Carry on doing this, always stroking the same way (like stroking a pet). This lines up the spins of the unpaired electrons in the iron, cobalt or nickel, which is what makes it into a magnet. The longer you keep stroking, the better the magnet you will get.

If you don’t have an existing magnet, you can try dropping your piece of metal hard, or heating it up to very high temperature and letting it cool down. Both of these will encourage the electron spins to line up parallel to the Earth’s magnetic field. Some iron ores are magnetic, and they do this: early compasses (lodestones) were made using natural magnets.

Another way of making a magnet is to coil up a piece of wire (like a Slinky) and run an electric current through it. This will induce a magnetic field down the axis of the coil; you can make the field stronger by putting a bar of metal down the axis. Such a magnet is temporary – the magnetic field will go away when you turn the current off. They are called electromagnets. Many magnets used in industry are electromagnets, because the ability to turn the magnetic field off is very useful.