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I Does a conductor create magnetic field when moving?

  1. Aug 24, 2016 #1
    Magnetic field is created when electrons move in the conductor, as far as I know. In the electric circuit electrons move with a speed of few mm/s when the circuit is closed.

    So, if I took a piece of wire and moved it, would it generate magnetic field? I suspect not, but I am wondering what is the difference when electrons are moving in the electric field inside the wire, or when they are moving when we move the wire.
  2. jcsd
  3. Aug 24, 2016 #2
    When you move the wire, you are moving electrons and also the protons in the nucleus. As these charges are opposite polarity, the effects cancel out. When a current flows in a wire, the free electrons do the moving, whilst the remainder of the atoms, which are positive, are heavy and do not move much. So we see a movement of negative charge in this case.
    It is worth mentioning that when the electrons move, it is slow, but the charge involved is very great.
  4. Aug 26, 2016 #3

    David Lewis

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    Gold Member

    All that matters is how many electrons move through the conductor in a given time.
    The speed of the electrons (how far in a given time) is irrelevant.
  5. Sep 2, 2016 #4
    When you say the movement of electrons "is slow", how slow is that?
  6. Sep 2, 2016 #5


    Staff: Mentor

    See https://en.wikipedia.org/wiki/Drift_velocity, under Numerical example.

    In their calculation, the electrons in a 2mm diameter wire with a 1 A. current are moving at about .02 mm/sec.
  7. Sep 2, 2016 #6
    Wow! Fascinating article. Just read over the gist of it and even with my rudimentary math skills, the numbers are fascinating. Thanks for sharing. I'd never have thought to look up "drift velocity".
  8. Sep 2, 2016 #7


    Staff: Mentor

    I wouldn't have, either. I looked up "electron speed in a wire" and followed a link on the wikipedia page to their page on "drift velocity."
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