Let's say that we have two parallel, vertical wires with radii much smaller than lengths.

The wire on the right is driven with an AC current. When the current is increasing in the upwards direction a changing magnetic field is generated out of the page (calculable by Ampere's law).

The changing magnetic field induces an electric field parallel to the two wires which induces a current in the wire on the left (assuming the wire has some resistance/resistivity and applying ohm's law).

Now for the question: does the induced current flowing in wire 2 (on the left) affect the current flowing in wire 1 (on the right)?

It seems like this is never taken into account because it is not practical/measurable but it seems to me that there would be some diminishing affect of each induced current back on the driving wire. How does this change with a change of load (inductive?) on wire 2?

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    $\begingroup$ So, back-EMF? Yes. $\endgroup$ – Jon Custer Jan 30 at 14:13
  • $\begingroup$ As energy (Joule effect) is dissipated in the conductor 2, it is necessary that this energy is provided by the generator which feeds the conductor 1. What you describe is a transformer and the back emf (flux from the secondary to the primary) allows to understand the transfer of energy. (sorry for my poor english !) $\endgroup$ – Vincent Fraticelli Jan 30 at 19:28

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