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Zero resistance?

  1. Mar 1, 2008 #1
    As an interested non-physicist, may I ask a possibly naive question concerning superconductivity? It seems that every reference I ever see regarding superconductivity, they always refer to resistance as zero. Now, I've had the opportunity in my previous work to measure large currents in MRI magnets and it always impressed me to see not one whit (engineering term) of decrease in current over periods of years of uninterrupted service. Still, the concept of zero resistance is so counterintuitive, even after reading about cooper pairs, etc, that I've always wanted to ask:
    Is it literally zero or some really low but non-zero figure?
  2. jcsd
  3. Mar 2, 2008 #2


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    It is literally zero in the sense that the upper bound for the resistivity is set by experimental capability - no experiment I know of has measured a non-zero voltage drop across a SC that exceeded the minimum resolvable signal.
  4. Mar 2, 2008 #3
    Thanks for the reply. So I'll assume that there is no theoretical basis for a resistance, which is what I was wondering. Still, with the resolutions available to experimenters these days, it is interesting that no resistance has been measured.
  5. Mar 3, 2008 #4
    There is rf resistance in superconductors.
  6. Mar 3, 2008 #5


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    I'm guessing the OP has only DC resistance in mind. Besides, the AC resistance has more to do with charge carriers having a non-zero mass.

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