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Q & A: magnetic levitation?

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Most recent answer: 10/22/2007
Q:
Hi I was wondering are there any magnetic like material in the earth?And if so is it possible to repel that and create some kind of levetating skate boared, with some strong magnets on the bottom of the board?Also what kind of magnets would I have to use?
- Yuanwen (age 12)
Westwood,Ma,USA
A:
The Earth is certainly magnetic. Its magnetic field is what makes North-South compasses align. The field is not nearly strong enough, or different enough from place to place, to use in any sort of levitation scheme. Even if it were stronger and had the right sort of spatial variation, any levitation with magnets would be unstable. perhaps you could actively adjust for that to stay levitated. With intense magnets and superconducting materials, stable levitation can be obtained. That's not practical for a skate board.

Mike W.

You'd also need a special surface, either made up of superconductors or magnets (if you want to reduce the weight and expense of the skateboard, you might want to make the underlying surface out of electromagnets with special feedback systems which supply the right push to keep the skateboard up).

I've seen a coil with a large alternating current flowing through it levitating above a thick (about half an inch) aluminum sheet. Eddy currents in the plate partially expelled the magnetic field from the aluminum. The whole thing got hot very quickly, though, and it was barely able to lift up the weight of the coil of wire, let alone a skateboard with someone on it. It sounds expensive and impractical.

Tom

(published on 10/22/2007)

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