[Corvettaholic]

So I was rummaging through old stuff at work one day, and I came across a dead SCSI hard drive. Being true to my nature, I ripped out the big fat rare earth magnet. This thing is freaking huge, with a 1/4" thick steel plate mounted to it. This thing can smash fingers good if they get in the path of this magnet and a metal surface.

Now to play with it. So I poked it with a screwdriver. The driver stuck real good to the magnet itself, but when I touched the driver to the steel plate the magnet is mounted on, there is very little attraction. Why is this?

I'm guessing its because the steel plate is absorbing a good chunk of the magnetic energy available, and there is very little left to grab anything else. I guess its like picking up paperclips with an electromagnet, you can only pick up so many. Also, I think its safe to assume this steel plate is mounted directly on either the North or South pole, but I can't determine which one it is. Not that I really care either, its only one magnet. But if I had a bunch of these, I think I'd care then or risk turning my hand into a pancake.

[hafford]

Ok
 you stated you have played with electromagnets, how do i reverse the pularity. so it will repell a normal magnet?

[xiankai]

sounds just right.

if there's an iron core, it'll probably concentrate all the magnetic flux within itself

[mike]

you stated you have played with electromagnets, how do i reverse the pularity. so it will repell a normal magnet?

Reverse the direction of the current, this will reverse the magnetic poles.