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Superconductors and best conductors

  1. Jul 10, 2012 #1
    Hello Forum

    gold, silver, copper are the best electrical conductors are room temperature. But they cannot be superconductors: there is no finite, low critical temperature at which they become superconductors...

    But what if we could bring their temperature to 0 kelvin? I believe that all metals become superconductors (R=0) at o kelvin, correct?
    All materials? Even insulators, can be become superconductors at 0 k?

    thanks
    fisico30
     
  2. jcsd
  3. Jul 10, 2012 #2

    ZapperZ

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    There's a difference between a metal having "zero" resistivity and a superconductor. A superconductor has a stricter criteria, and, it is a "phase transition".

    One needs to look at the Meissner effect, and the different between a diamagnet and perfect diamagnet. It is clearly manifested when cooling in a magnetic field.

    BTW, most metals do not have zero resistance at T=0. There is something called residual resistivity that starts to creep up as one gets very close to 0K.

    Zz.
     
  4. Jul 10, 2012 #3
    Ok, thanks, I see.

    So silver does not have a critical temperature and it may not even have zero resistivity at T=0 K.....

    As far as the current flowing in superconductors go: I think the current can only be a surface current, regardless of it being DC or AC...
    Is that correct? If so, why?
    thanks
    fisico30
     
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