A conducting rod moving in a uniform magnetic field with a constant velocity is used as an example in textbooks, with charge moving from one end of the rod to the other and the amount of charge depending on the velocity of the rod and the magnitude of the magnetic field.

Does anything change if the rod is superconducting?


1 Answer 1


Not really. It will get to equilibrium slightly faster, but that probably wouldn’t even be measurable if being compared to a copper wire. The charges will still migrate to the point where the internally generated electric field cancels out the electric field being made from the charges moving in the field.

They will get to that point a touch faster because there is no resistance to them flowing. Some electric potential along the way is used to move them. But the final equilibrium charge distribution will be the same in both cases (as mentioned the distribution that makes an electric field equal and opposite to the one being generated).

  • 1
    $\begingroup$ Thanks, I was wondering since the magnetic field would go through the copper bar, but would not be present in the superconducting bar, if there would be a difference. I guess since all the charge would be on the surface it would still be the same. $\endgroup$
    – UVphoton
    Commented Aug 20, 2021 at 15:01
  • $\begingroup$ Yeah thats a good point. Yes on surface for both $\endgroup$
    – Al Brown
    Commented Aug 20, 2021 at 18:23

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