I'm going to demonstrate the force on a wire in a magnetic field. I'm producing this magnetic field with these U-shaped magnets. I've got a tunnel of them set up here: 1, 2, 3, 6, 8 of them. All of their north poles are on that side all of their
south poles are on this side. The wire is just a ribbon of aluminum foil. I'm going to provide the current with this power supply. I can get 20 amps of current from it. Before I do the demonstration let's talk about the magnets You can look
at these U magnets simply as bar magnets that were bent into a U. Let's see what the magnetic field would look like. Here's a bar magnet; the field of bar magnet is how you see on the board. Let's suppose that we took a bar magnet and bent it
into a U shape so now the poles are here and the field lines between the U magnet go directly from the north pole to the south pole. Beyond that you get some curvatures you see right there. Now we're ready to do the demonstration.