Magnetic Pendulums

Date: Tue Dec 29 1998 - 12:14:40 PST

Maria --

Your e-mail was forwarded to me, but it was already vacation when I received
it, and then Christmas took over. So I hope that this is still in time to be
of help. Here are some suggestions for the magnetic pendulums.

1. Be sure all electrical connections are good. If you are using enamel coated
wire, be sure that the enamel is scraped off the ends of the wires where you
join them. If there is plastic insulation on the wire, be sure to strip it
off. the ends where you join them.
2. Be sure that you are not using bare wires for the coils themselves, or that
the insulation has not been scraped off somewhere in the middle of the coils.
Enamel insulation is fine, but if somehow there is no insulation at all on the
coils, then you really just have a giant one-turn coil instead of the 50 or
more that you should have.
3. Be sure your magnets are cow magnets. These are stronger than many of the
old bar magnets sometimes found in schools.
4. Be sure that the coils are hanging so that they come to rest just at the
end of the cow magnets.
5. Be sure the coils are free to swing. If you're using #22 wire, you might
try a smaller diameter wire like #26. The finer wire is more flexible, and
allows the coils to swing more freely.

Beyond this I don't know what to tell you, without actually seeing your
construction. I've actually built one myself, and I've seen several others
built by others that worked, but this was all several years ago. But feel free
to contact me again if you still have questions. Good luck!

Don Rathjen
Exploratorium Teacher Institute

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