Questions about magnets.

[Al Skierkiewicz]

Originally Posted by Elgin Clock

Hey all, I'm working on a little project and I was wondering if anyone in the CD community had any answers to the following questions.

Does every magnet have a north and south pole? I would assume so.

If you break a magnet, do those individual pieces now have a N&S pole each?

What is the strongest pole?

What is the most effective way to shield from magnetic fields?

Where can I buy magnets besides at the hardware store?
The stronger the better (but still relatively cheap, and also lightweight).

Every magnet has a north and south pole no matter how large or small. (think really small on the surface of a magnetic floppy disk) When you break a magnet you get two magnets and they each have two poles. The poles are generally balanced so neither is stronger. Magnetic fields suscribe to the inverse square law so you can modify a little by putting non magnetic materials between the pole and magnet. Round magnets get a little complicated and some motor magnets have multiple NS pairs but are really individual pole pairs in the same material. Ferrous metals are good for magnetic shields especially those that have high nickel and carbon concentrations. They are more bending the field away than actually shielding. Check out science stores like "the American Science Center" or industrial supply houses like McMaster-Carr. The cheapest are those you salvage out of dead devices, like DC motors, VCRs, disk drives, etc.