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Q & A: levitation

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Most recent answer: 10/22/2007
Q:
Hello, I’m Nichole Lively. I was wondering, if it was possible to make an object float in air using magnets? How would I be able to do such thing? Thanks,
- Nichole Lively (age 12)
New Brunswick, Canada
A:
This is a common question -- please search our Question and Answer archives using the word "levitation".

You cannot get any ordinary object to float with any fixed combination of magnets. There will always be some way that it will slide out or flip over or somehow escape. By 'ordinary object' I mean one whose magnetism tends to line up with the applied field on it. (The impossibility of simple levitation for such obects was proven mathematically by Earnshaw.) Now many objects are 'diamagnetic', which means that their magnetism actually lines up opposite to the field. In almost all cases, that effect is too weak to support the object. The one major exception is due to superconductivity, since superconductors are very strongly diamagnetic. It's pretty easy to float a small magnet above a superconducting ring. However, the ring has to be kept very cold, since no room-temperature superconductors are known.

Another way to use magnets to make something float is by constantly adjusting the magnetc field to counter any slippage. This can be done with electromagnets and cleverly designed electronic circuits.

Mike W.

(published on 10/22/2007)

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