How electromagnetic fields travel through vacuum is it right to say that they propagate or travel? do they alternately form each other by charged particles?
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You see, there's a difference between being generated and being able to travell. Electrodynamic theory grants that electromagnetic waves can travel in vacuum, but where the wave is generated is another thing. – Gold Apr 07 '14 at 21:45
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1It travels on the aether! :) – Chris Mueller Apr 07 '14 at 22:50
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The magnetic field produces an electric field and in turn electric field produces a magnetic field explanation of propagation is often cited but wrong. – Brandon Enright Apr 08 '14 at 05:54
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1Possible duplicate: http://physics.stackexchange.com/q/156606/50583 – ACuriousMind Nov 28 '16 at 17:19
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from a, b and c:
An electromagnetic field is propagating by changing the field that's generated by electrically charged particles pass through the air and the space that is devoid of particles of space.
An electromagnetic wave propagates, not an electromagnetic field. An EM wave is a propagating disturbance in the existing electromagnetic field.
Consider the field of an isolated charged point particle - the field extends over all space.
Should the particle abruptly accelerate for some short time, the disturbance in the electromagnetic field of the particle will propagate 'to infinity' at the speed $c$.
From the classic textbook "Gravitation":
For an animated visualization, try the Java applet here.
Alfred Centauri
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electromagnetic fields exist at all points. Disturbances (waves) propagate through them. The field cannot propagate because it already is everywhere it can go – Jim Apr 08 '14 at 16:43
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@user37421 the field is a description a state. It describes the state that changes over time when a EM wave is present. – Volker Siegel Apr 09 '14 at 01:34
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1One can shield a region of space from having any electromagnetic field with the aid of a Faraday cage. According to this argument light cannot propagate in a Faraday cage, which is obviously not true. Light does not require the existence of a "field" to propagate as a "disturbance." The wave is also a field. – flippiefanus Nov 24 '16 at 14:55
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@flippiefanus, I don't agree with your claim that "One can shield a region of space from having any electromagnetic field" - the electromagnetic field exists everywhere. – Alfred Centauri Nov 24 '16 at 15:24
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"the electromagnetic field exists everywhere" --- how do we know that? – flippiefanus Nov 25 '16 at 04:24
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@flippiefanus, the fact that $\vec E(\mathbf{x})$ and / or $\vec B(\mathbf{x})$ is zero in some region logically requires that $\vec E$ and $\vec B$ exist in that region to take the value of zero. – Alfred Centauri Nov 25 '16 at 11:23
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OK, so "exist" does not mean it is nonzero. In my view that does not mean the same thing, but this is not worth arguing about. In essence we agree. – flippiefanus Nov 25 '16 at 11:43
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The electromagnetic field is mediated by the exchange of virtual photons. This is described by Quantum electrodynamics. It's this exchange that bridges the gap of empty space.
I think the answer to this question has a pretty good representation of how an electromagnetic field propagates (at the speed of light) in vacuum.
