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In all the examples of generation or existence of Magnetic Field energy I have seen so far, I couldn't find any example, where magnetic field energy is created without Non Conservative Electric field, which in turn is generated by Time Varying Magnetic Fields. So, would it be right to generalize that the only source of Magnetic Field energy is, Non Conservative Electric Field?

I am aware that current carrying wire generates magnetic field around it, but I believe that is also caused by the Non Conservative Electric Field, which came into existence into the circuit, when current was building into it, due to the Self Inductance of the wire. Initially when the current was building, the current was variable and so the magnetic field around it was variable, which gave rise to non conservative electric field, which extracted some energy from the source and stored it in the magnetic field around the current carrying wire.

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Magnetic field is produced by moving charges. So, whatever energy source can move charges, could be a source of the magnetic field energy associated with the moving charges.

Besides the time varying magnetic field, charges could be moved by static electric field, heat (thermionic emission), light (photoelectric effect) or mechanical action (vibrating a charged glass rod).

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  • $\begingroup$ I agree with you. I also believe Magnetic Field Energy creation must be MEDIATED by the Non Conservative Electric Field, in all the cases you mentioned and that is what I intend to ask in this question. Kindly comment. $\endgroup$ – Devansh Mittal Aug 31 '18 at 18:49
  • $\begingroup$ @DevanshMittal Could you point to a reference to back up that statement? $\endgroup$ – V.F. Aug 31 '18 at 19:09
  • $\begingroup$ I do not have any reference to back that statement, but in all the examples I notice magnetic field energy, in all such cases, somewhere during its creation, the time varying magnetic field must have come into existence, which gives rise to Non Conservative Electric field. Don't you think so? This is why I say, magnetic field energy is mediated by non conservative electric field. Could you point to any counter example? Kindly also read my comments to Emilio. $\endgroup$ – Devansh Mittal Aug 31 '18 at 19:19
  • $\begingroup$ My understanding primarily follows from the example of an Inductor. In an inductor, the work done by the Non Conservative Electric Field, turns out to be equal to the energy stored in the Magnetic Field Energy. It is true that this energy comes from the source (battery for example), but the conversion of energy is mediated by Non Conservative Electric Field. Isn't it? $\endgroup$ – Devansh Mittal Aug 31 '18 at 19:33
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    $\begingroup$ @DevanshMittal When the current and its magnetic field is increasing, a non-conservative electric field is created, but, in this case, it is the effect - not the cause - of the changing magnetic field. I am far from claiming that this exhaustively describes what is going on, but I would not speculate what else might be happening that could potentially invalidate this logic. $\endgroup$ – V.F. Aug 31 '18 at 20:42
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No.

Any static electric current will generate a magnetic field which is not attributable to a non-conservative electric field. I'm unsure why you haven't been exposed to that example, but you can find it in the introductory section of the magnetism chapter of pretty much every textbook on electromagnetism.

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  • $\begingroup$ Thanks for your response. I am aware that current carrying wire generates magnetic field around it, but I believe that is also caused by the Non Conservative Electric Field, which came into existence into the circuit, when current was building into it, due to the Self Inductance of the wire. Initially when the current was building, the current was variable and so the magnetic field around it was variable, which gave rise to non conservative electric field, which extracted some energy from the source and stored it in the magnetic field around the current carrying wire. $\endgroup$ – Devansh Mittal Aug 31 '18 at 18:42
  • $\begingroup$ Bold face is appropriate here! $\endgroup$ – garyp Aug 31 '18 at 18:45
  • $\begingroup$ @DevanshMittal That is incorrect - it is perfectly possible to set up an electric current using a conservative electric field, and the only way that the transients generated at start-up can be interpreted as "creating" the field is if you have a personal sui generis re-definition of that term. But if you've already decided what you will or won't believe, there's absolutely no point in discussing it. $\endgroup$ – Emilio Pisanty Aug 31 '18 at 18:59
  • $\begingroup$ @Emilio Pisanty - Thanks for your response. I am definitely open to learn and revise my understanding. Kindly help me further. If I understand right, a steady current is not achieved instantaneously. It will take some time to reach, and during that time, the current is variable, so thus the magnetic field, which will result into the production of Non Conservative Electric Field. Isn't it true? If Yes, then can't we say that the creation of magnetic field energy around a current carrying wire is MEDIATED by the Non Conservative Electric Field? $\endgroup$ – Devansh Mittal Aug 31 '18 at 19:03
  • $\begingroup$ That is technically correct, but it is perfectly possible to do an adiabatic ramp-up of the current, where you turn the current on slowly, which makes that component negligible. For any (continuous) measure of the non-conservative component of the electric field that you care to name, it can be made arbitrarily small by making the ramp sufficiently long. $\endgroup$ – Emilio Pisanty Aug 31 '18 at 19:11

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