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Wires and potential difference

  1. Mar 16, 2010 #1
    Recently in physics I've learned that equipotential surfaces are always conductors in electrostatic equilibrium.. so no moving charges. I'm a little confused, then, of how a wire carrying current is considered an equipotential? If charges are moving how can the potential be constant?
  2. jcsd
  3. Mar 18, 2010 #2


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    Science Advisor

    I don't understand your question because a wire with current moving through it is NOT an equipotential surface- for one thing, in order to have current there must be a potential difference between the two ends. Of course, in order to have a current in it, differing potential must be applied to both ends of the wire. A wire without an imposed potential difference is an "equipotential"- and has no current in it.

    (Since this is a question and NOT "learning material" I am moving it to "general physics".)
    Last edited by a moderator: Mar 18, 2010
  4. Mar 18, 2010 #3


    Staff: Mentor

    HallsofIvy is correct, however if you are in a circuits class then you will often make the useful approximation that the ends of a wire are equipotential because it is simply too tedious to keep track of a couple of nanovolts here and there.
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