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I teach high school physics and I'm trying to put together a correct explanation for the levitation of a superconductor above a magnet without a high level of quantum mechanics (but consistent). I have seen several explanations online and in text books. Many of them say Lenz's law is not part of the explanation for the situation. I'll propose an explanation and hopefully someone can comment on what is correct and incorrect about it.

  1. A superconductor is sitting on top of a magnet and the superconductor is cooled below its critical temperature. The Meissner effect results in the exclusion of the external magnetic field from the superconductor.

  2. The exclusion of the internal magnetic field creates a changing magnetic field on the surface of the superconductor which induces a current in accordance with Lenz's law (many sources I have found say that a surface current is created on the superconductor).

  3. The induced magnetic field from the surface of the superconductor repels the magnetic field of the magnet and the superconductor rises above the magnet until the force of gravity is balanced by the magnetic repulsion.

Note: I know that flux pinning is at play to contribute to the stability of the situation but I am just interested in clearing up the basic physics of how the levitation is possible.

So, are there surface currents? Is my explanation above consistent with current understanding of the situation? If anyone knows someone who I should contact directly who could help me that would be wonderful.

Thanks.

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marked as duplicate by Dan, Chris White, Manishearth Jul 12 '13 at 6:08

This question has been asked before and already has an answer. If those answers do not fully address your question, please ask a new question.

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possible duplicate of What is "quantum locking"? –  Ali Jul 6 '13 at 14:43
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Another possible duplicate, worth checking out the answers of: physics.stackexchange.com/q/48421/16660 –  Wouter Jul 6 '13 at 14:52
    
Another possible duplicate: physics.stackexchange.com/q/15855/2451 –  Qmechanic Jul 6 '13 at 16:38
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