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Behavior of conductor

  1. Mar 22, 2015 #1
    What will be the behavior of conductor at absolute 0 temperature?
     
  2. jcsd
  3. Mar 22, 2015 #2
    I think the answer would be different for different materials.
    We do know however that some materials become superconducting, offering virtually no resistance at all, even at temperatures somewhat warmer than absolute zero, although still very cold.
     
  4. Mar 22, 2015 #3
  5. Mar 22, 2015 #4

    ZapperZ

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    This is incorrect. Just because something may have zero resistance, it doesn't mean it is a superconductor. Superconductivity is a "phase transition", meaning that it gets into that state abruptly at a finite temperature. It also needs to exhibit the meisner effect, something that is not exhibited by a "perfect conductor"

    However, also note that all REAL conductors that do not exhibit superconductivity actually DO NOT get to zero resistance as the temperature approaches 0K. There is something called http://www.nist.gov/data/PDFfiles/jpcrd155.pdf [Broken] that is present and will cause the resistance to deviate and not get to zero at 0K. So not only do they not become a superconductor, they also will not have zero resistance!

    Zz.
     
    Last edited by a moderator: May 7, 2017
  6. Mar 22, 2015 #5
    I didn't say that it's a superconductor because it has zero resistance, I said that a superconducting material loses all of its electrical resistance. Is that incorrect? I meant that some conductors become superconducting at temperatures higher than absolute zero, so at absolute zero they would still be superconducting(is that correct?). Are you saying that I am incorrect because the way I said it, it implied that all conductors can become superconducting? I was referring to the conductors that do become superconducting because I assumed that was what the question was about, was it not? Are you saying that in a superconductor, some electrical resistivity will always be present because of residual resistivity?
     
  7. Mar 22, 2015 #6

    ZapperZ

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    Zero resistivity is only ONE requirement for a superconductor. So your original claim that at T=0, "... It will become a superconducting material and will lose absolutely all of its electrical resistance..." is incorrect. This is because there are OTHER properties that must be satisfied for a material to be a "superconductor", not just zero resistance. You should look at the difference between a "perfect conductor" versus a superconductor (see what happens with those two in field-cooling scenario).

    Where exactly in the original question can you deduce that?! The OP asked this: What will be the behavior of conductor at absolute 0 temperature?. And you somehow deduced that he/she is asking ONLY for conductors that become superconducting?!

    Again, you are either reading something incorrectly, or reading something that isn't there! This is what I wrote:

    Pay attention to the bold phrase!

    And for your further education, the zero resistivity even in a superconductor is only true for DC resistivity. There is a non-zero AC resistivity even in superconductors!

    Zz.
     
  8. Mar 22, 2015 #7
    I'm well aware that you know far more than me on this subject, but I said that zero electrical resistivity was caused by becoming superconducting. Not becoming superconducting because it conducts electricity perfectly. I also said, "among other things," notifying that there are other properties of a superconductor. I only mentioned the one about electrical resistivity because it was the main one that came to mind.

    I assumed that was what he/she was asking about, and I don't know about what would happen if it was a conductor that couldn't become superconducting, so I didn't say anything about that.

    Out of curiosity, what would happen to, for example, copper at zero K?
     
  9. Mar 22, 2015 #8

    ZapperZ

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    Whatever it was that you were trying to convey did not come out right. That was why I had to step in and correct the impression that every metal becomes a superconductor at T=0K. This is false.

    That is a very strange assumption, considering that you are ignoring a large part of the the world of "conductors". That's like answering the question: "What happens to cows after they are slaughtered?" by saying "Oh, they all become hamburgers.".

    Read the link I gave!

    Zz.
     
  10. Mar 22, 2015 #9
    Okay, I'm fairly certain that, by now, the initial question was thoroughly answered.

    Out of curiosity, deependra1003, did you want to know about conductors in general, or potentially superconducting conductors?
     
  11. Mar 23, 2015 #10
    Guys , I just wanted to know about the conductors only.
     
  12. Mar 27, 2015 #11

    marcusl

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    The resistance of normal conductors drops with decreasing temperature, essentially because vibrations of the crystal atoms (phonons) decrease and hence cause less scattering of the current-carying electrons. Some scattering remains even near 0K due to imperfections and impurities in the crystal lattice. This is why normal metals cannot reach zero electrical resistance. The low-temperature resistance floor is often characterized by the residual resistance ratio RRR (you can look it up).
     
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