Date: 07 Nov 2002 14:59:18 -0500

Author: Michael Timmins

Subject: Re: mod on eddy current


We do this with a square copper rod connected end to end with a square
plexiglass rod. A notch is cut in both the copper and plexiglass so
that a small cylindrical magnet can roll in it. When tilted, the magnet
rolls quickly through the plastic notch and comes to a slow crawl when
it hits the copper. The whole thing is enclosed in plexiglass so it can
be handed around the class without losing the magnet.


On Thu, 2002-11-07 at 10:35, Sam Sampere wrote:
> I bought some of those cool NdFeB magnetic spheres for various demos.
> Here's a way cooler way to show the Eddy current tube.
> First, roll the ball down a long piece of flat plastic. It's not very
> spectacular, you get just what you expect. Then roll it down a long
> piece of copper. I'm using a piece of 1/8" x 8" x 36" OFHC. The ball
> very slowly rolls down the new incline. Repeat this several times until
> the copper is vertical. It's just too cool!
> The sheet is much cheaper than the thick walled tube, and much lighter
> too.
> Sam
Mike Timmins
Department of Physics
382 McCormick Rd
University of Virginia
Charlottesville, VA 22904-4714
Voice: (434)924-6800