In this example:

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and many others related to electromagnetic induction, the main component of motion would be the conductor perpendicular to a magnetic field.

I know it's possible to have it the other way around, fixed conductor and move the magnetic field source (e.g., magnets, electromagnets), but I'm curious of the type of force the magnetic field source would experience when current flows.

In a typical generator (where the wire rotates around a fixed magnet(s)) there is an induced EMF ($vBL$) and current will flow to the load, and due to the induced EMF is opposing the change in magnetic field flux, the Lorentz force acting on the wire will oppose the applied motion ($v$). What about the case when the magnet rotates a fixed conductor? Will it experience an induced Lorentz force opposing the motion?


1 Answer 1


Yes, induced electric field around the magnet will produce current in the static conductor, energy will get dissipated in it and kinetic energy of the magnet will decrease.

  • $\begingroup$ Will the magnet experience a Lorentz force, or a magnetic attraction/repulsion force due to the static conductor's magnetic field opposing the change? $\endgroup$
    – Pupil
    Commented Dec 6, 2015 at 13:07
  • 1
    $\begingroup$ The conductor's EM field will not be static in general. In any case, the magnet will experience ponderomotive force both due to itself and due to the conductor. Its expression in terms of fields and other variables might be trickier than using the simple Lorentz formula for EM force involving charge and current density. $\endgroup$ Commented Dec 6, 2015 at 14:33

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