The concept of production of electromagnetic wave from oscillating charge is already understandable. The oscillating charge creates electric field and created electric field induces magnetic field. The induce magnetic field also create electric field in opposite direction as shown in Figure.
But my question is that, how magnetic field is created?
At quantum level which things or phenomena lead to the production of magnetic field.
Same question is arise in Oersted experiment?
A very good question , one that has puzzled me for several decades. One answer is that is what maxwell's equations predict and they get the wave speed in a vacuum correct , so all is ok . Another answer would be actually the EM wave is a stream of particles ( photons ) whose internal mechanism, if any i, just like the electron, is unknown , possibly unknowable !!! In other words I do not know but am sure nobody else does in 2018
See the differential version of the Ampere's Law, it predicts a magnetic field when you have an electric field that changes over time.
Dear Herman heffner
I understand the production phenomena through mathematically Maxwell equations. but my doubt is that, what happens in physically at quantum levels and how magnetic filed is created.
You are not alone ! I have come to the conclusion that the photon is simply still a mystery , on the same level as the electron . We understand a great deal about how both electrons and photons interact with other matter and fields but have no idea about their internal mechanisms . We have to accept their measured properties / attributes eg electron charge , mass and spin or photon wave length , energy , polarisation . We have no means to probe the electron's inner properties . and the same is true of the photon. All that simply means we don't really understand QM . We know pretty well how to use it but that is where intuitive understanding stops.
It is strange and unusual in the history of physics ( over the past 3 /centuries )that progress has simply come to an almost grinding halt and stayed there for over 60 years. Possibly we have hit a limit . I like to think the next generations will crack it, just out of curiosity, but not anytime soon. There is no economic pressure to go deeper . What we already know is more than enough for civilization to prosper for 100+ years and there are much more pressing problems for humankind which are just as challenging and interesting .
Oh well, I think you might want to take a look at this article that tries to explain the origin of the magnetic field.
Article Twisting Space-Time: Relativistic Origin of Seed Magnetic Fi...
Well who knows ? looks like about 100 other speculations that do not really touch the basic worry about classical physics. and certainly don't look viable bases for calculation. We are not at all happy with action at a distance'cos it seems like magic ( newton worried about it as well) . That rules out the whole classical notion of fields of force. Having said that the field notion works a treat in many many circumstances and is lot less hassle than fiddling with the exchange of virtual particles whose properties we don't know either. What you have to ask about these speculations is do they actually provide a new practical way of doing physics . Nearly always the answer is no
Dear all: my guess is that, from an QED point of view, the electric and magnetic fields in an e.m. wave support one another through virtual charges that are created and destroyed in quantum vacuum, but coherently. But it is just a guess! I agree with Chris Guy's when he says that at 2018 nobody knows what is really happen!!! Greetings!
Jose. A good guess I reckon ..but of course that makes the EM wave infinitely more complicated to handle ( I don't think radio engineers would dream of thinking in any other terms than fields) If only Maxwell's ether actually existed !!! Perhaps it does and that is, sort of ??, what Vac coherent fluctuations are . Another perhaps is this. If we didn't start with Maxwell , rather with photons with integral spin then the only problem is just how dense streams conspire to behave just like a tangible, macroscopic , coherent travelling wave. Yes they are Bose particles , so far so good but no since as far as I know photons in free space do not interact .. or do they ? Well we have been stuck for 60 years so quick answers are unlikely to be correct.
Dear Guy: yes, photons interact as real particles but through virtual particles of the quantum vacuum. It is the well known photon-photon interaction (not included in the linear Maxwell´s classical formulation), related to the Delbruck effect. If somehow the classical fields couples with virtual currents in the quantum vacuum, then they can born magnetic fields and viceversa. Of course, I don´t know who is the ingeneer that will do a calculation using QED, but certainly Maxwell's equations will be enough for him!!! The photon-photon interaction is a purely QED effect
Don,t know of the Delbruck effect . please advise on the circumstances in which it occurs.
Do Know
Two intersecting light beams pass through without interaction ( IN FREE SPACE) and radio antennas are designed ( Very well !!) assuming the linear superposition of fields from the several component parts. I conclude there is no significant photon -photon interaction IN FREE SPACE.
Perhaps it is not needed if all the photon particles have a tendency towards a single state .. but this would seem to be an interaction . I think all B.E effects in solids and liquids ( Supercon. and superfluid etc ) need ,or at least have, significant particle particle interactions. Still a puzzle then !
Dear Guy: yes, you are right, there is no significant photon-photon interaction in free space, but still there it is. I mean that QED effects are beyond the linear formulation of Maxwell ED; in fact they arise as weakly non linear terms in the lagrangian of interaction. So photon-photon scattering is extremely weak. But if you ask me about how to explain the origin of the magnetic field in a real e. m. wave I can suppose (only as a guess!!!) that the E field generates coherent virtual currents of virtual charges in the QED vacuum, and those are the origin of the B field, and reciprocally. But again: it's just a guess!!! I really don't know how an QED process generates de B field in a classical e.m. wave!!!
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