Message-Id: <v01540b1ab13c9b14a50b@[192.174.2.173]>
Date: Mon, 23 Mar 1998 15:12:39 -0800
To: pinhole@exploratorium.edu
From: pauld@exploratorium.edu (Paul Doherty)
Subject: Re: Pinhole Daily Digest
Hi John
There is an article on building your own levitron in the American Journal
of Physics a few years back. Their conclusion is that it is very difficult.
You have to get the gyroscope magnet weighted to within a small fraction of
a gram, and the base magnet has to be level.(It actually has a good moral
to it, the inventor was told by every physicist that what he wanted to do
was impossible, in the end the physicists were wrong they had mis-used
Earnshaw's theorem which says that stable magnetostatic levitation is
impossible. The levitron has a moving piece that makes it not static.
A few hints, we level the base magnet using a circular bubble level and
placing the magnet on a plastic base with adjusting screws to change its
levelling forget the plastic wedges!
The experts take a block of base magnet material, rectangular or circular
in cross section an inch thick and solid, and reverse magnetize a region in
the center by touching it with a cylindrical neodymium magnet 1 inch long
and 3/4 inch in diameter.
In the end, so far at least, it is cheaper to buy a comercial kit than to
build your own. However I keep hoping someone will hit on the right recipe!
Keep up the good work.
Paul Doherty