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I A circular current-carrying wire floats in space...

  1. Feb 16, 2017 #1
    Maybe there's a tiny battery somewhere, just to make it realistic. The wire is also very thin, and thus needs little to no force to be bent.

    What happens to the wire? Does it twist on itself because each piece of the wire experiences a Lorentz force due to the magnetic field of the wire on the other side of the circuit?

    EDIT: Just did some sketching, it looks like the forces point inward indeed. So, I may have answered my own question :)

    EDIT 2: Correction, the forces point outward. That could mean it is self-stabilizing, since any part of the wire going outward (experiencing less magnetic field as a result) would require another one to go inward (experiencing more field).
    Last edited: Feb 16, 2017
  2. jcsd
  3. Feb 16, 2017 #2


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    I am not sure if I understand the scenario clearly. Is the force acting on the wire because of its own field?
    The field of a circular current carrying loop looks like this. images (7).png
    It appears from the diagram that there is no field at the site of the wire.

    In all the situations that I have seen before, where there is a force on a current carrying conductor, it is because of the magnetic field from some other source (e.g in dc motors, short circuit fault in transformer, PMMC, MI or EDM type measuring instruments etc.)
  4. Feb 16, 2017 #3
    Yeah, I'm considering only the forces the wire exerts on itself.

    Hmm, the pic you posted would suggest there is no magnetic field inside any of the wires. That's just a simplification though, right? There should be a minor magnetic field due to the magnetic field originating on the other side. Or is this one of those cases where everything exactly cancels out so that there really is no magnetic field inside the wire?

    The way I'm imagining this is an extension of the classic "two parallel current-carrying wires are exerting forces on each other", only in a circular sense.
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