Great question! What you're talking about doesn't just have to do with windmills - any
time you move a magnet near a wire, you will get electricity. This is how all electric generator works.
As you know, if you hold two magnets close together there will be a
force between them. What you perhaps didn't know is that if you move a
charge (like an electron) near a magnet, it will also experience a
force. It is this kind of force that is used in your TV set to focus
the electron beam and make the picture.
OK, if you believe that a moving electron experiences a force in a
magnetic field, the rest is easy. A copper wire has lots of electrons
in it that are free to move around inside the wire (copper is a good
conductor). If you move a copper wire near a magnet in the right way,
the magnetic field will try to push all of the electrons in the wire in
one direction. This is how a generator works. You have lots of loops of
copper wire that is moved (in a circle as it turns out) close to a
bunch of strong magnets. This causes electrons to move in the wire.
Since moving electrons are just electric current, presto, you are
Tamara & Mats
(republished on 08/02/06)