The two types of magnets that we encounter most in everyday life are permanent magnets and electro-magnets.
magnets are made from metals in which tiny regions, called domains,
each act kind of like a little bar magnet. Although they tend to be
pointing randomly, these little domains can be partly aligned resulting
in the bar magnets we have all played with in school. If you broke a
bar magnet in half, each half would have a north and a south pole, just
like the original only smaller. You can change which end of a bar
magnet is north by using a stronger magnet to flip the orientations of
some of the domains.
Electro-magnets are the kind of magnets that you get when you wrap
an electrical wire around a nail and pass a current through the wire.
With this kind of magnet, you can change how powerful it is by changing
how much electric current is flowing in the wire (for example, by using
more batteries). You can also change where the poles are just by
changing how you have the wires hooked up.
If you want to order a high power magnet, you can find them in
science supply catalogs or at science stores. One good place to find
them in things you may have around is if you have a really old computer
that you don't want anymore. (Make sure it's one you're absolutely sure
you don't want to use /ever/ again.) Inside the hard-drive, there are
some extremely strong magnets that you can get out if you take it apart
(republished on 07/13/06)