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I Self inductance of a superconductor

  1. Feb 8, 2017 #1
    Hi.

    Superconductors can be made hover above or even below magnets. As far as I know, this can be interpreted as an extreme form of Lenz's law: Eddy currents on the surface of the superconductor create an opposing force that is able to cancel gravity since the currents aren't affected by resistance.

    By that logic, shouldn't a superconducting coil have infinite self inductance and thereby be not conducting at all? Shouldn't turning on a current create a current of the same magnitude but opposite direction in neighboring loops so they exactly cancel?
     
  2. jcsd
  3. Feb 8, 2017 #2

    Baluncore

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    It is the internal currents that cancel. The external currents do not.
    There is no problem inducing a current to flow on the surface of a superconductor. The filaments of current that flow along the surface of a superconductor are coupled to each other. Likewise other parts of the same conductor that are further away couple less. Self-inductance is a function of the magnetic coupling of the conductor to all other parts of itself, quite independent of the resistance of the conductor.
     
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