TITLE: Loop of wire in a varying magnetic field
QUESTION [3 upvotes]: Let us suppose we have a loop of wire with some definite resistance in a magnetic field. Let the magnetic field be varying. This varying magnetic field will st up an EMF in the wire. My questions are as follows:
1). Energy is dissipated across the wire resistance. Where does this energy come from?
2). The current generated in the loop will also generate a varying magnetic field. Will this magnetic field induce another EMF in the loop setting up another varying magnetic field? Will this go on indefinitely?

REPLY [4 votes]: 1) The energy comes form the aperture that creates varying magnetic field.
2) The process you describe (Lenz law) is fast convergent, since the induced magnetic field is much much smaller than the outer magnetic field.  The process is instantaneous, so current within loop and total (outer and induced) magnetic field are immediately in the equilibrium.
{"set_name": "stack_exchange", "score": 3, "question_id": 29569}