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Let a square loop be placed in a uniform electric field in a position of stable equilibrium.

Then, because of the electric field, if the electric field is in the rightward direction then a positive charge will be developed in the rightward direction and negative charges will be developed in the leftward direction. Thus an emf is generated between the left side and right side points; so a magnetic field is induced in it and it will interact with the electric field.

Interaction means force, so why do we say that no force acts on a square loop when placed in a uniform electric field?

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    $\begingroup$ A time-varying magnetic field induces an emf in a loop, not the other way around (and even here, there is no net emf around the loop). It is not clear what you mean by "[the magnetic field] will interact with the electric field". $\endgroup$
    – AV23
    May 5 '15 at 17:00
  • $\begingroup$ Doesn't equilibrium mean the net force is 0? I don't think it is applicable to talk about individual forces, but over all there wouldn't be a force on the loop. $\endgroup$ May 5 '15 at 17:43
  • $\begingroup$ @AV23 you're wrong about the loop comment. Maxwells equations without currents: curl(E) = -dB/dt, curl(B) = (1/c^2) * dE/dt $\endgroup$ Dec 22 '15 at 6:50
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    $\begingroup$ @aquirdturtle Ok. I guess what I should have written is a simple emf between two points does not generate a time-varying magnetic field. $\endgroup$
    – AV23
    Feb 7 '16 at 17:22
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There are many problems in your question. First, stable equilibrium often applies to the state of a current loop sitting in a magnetic field. A electric field may charge the loop by induction(move the charge), but it will not induce a current(a continuous flow of charge) inside the loop. The charge inside the loop will eventually reach electrostatic equilibrium due to the counter electric field created. Magnetic induction refers to a situation where a continuous current flow is induced when there is a changing magnetic flux. Finally, "magnetic field will interact with electric field" is not an accurate statement. Changing electric field induces magnetic field and changing magnetic field will induce electric field. There are many good resources you can learn more about this topic. You can try an online course on edx if you really want to learn electricity and magnetism systematically.

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I think that the quick answer to what you are trying to get at is that the temporary currents induced in the wire loop are negligible on any reasonable time or magnetic field scale, and that the magnetic fields induced by this charge don't actually "interact" with the electric fields the way it sounds like you are implying.

The only way electric and magnetic fields "interact" is that a changing electric field produces a magnetic field and vice-versa; there's no clear force to define there. Electric and magnetic fields do interact with charged particles in a way that clearly implies a force.

Also, I think you should be careful with the statement "interaction means force", especially when considering quantum mechanics.

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