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I have a doubt about electromagnetic waves. Can we say that a static electric field is still composed of waves, even if they don't spread in space (as the field is static and so it doesn't evolve over time)? And if this is the case, why do we draw the elctric field lines, for example for a point charge, as radial lines, while the waves should propagate radially and thus the electric field vectors should be perpendicular to the radial direction?

Thank you!

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By Maxwell's equations, electromagnetic waves consist of time-varying electric and magnetic fields. In order to create electromagnetic waves, you must have some time-varying behavior in your system. Therefore, a static system cannot generate electromagnetic waves, nor can an electrostatic system be described as "composed of waves" (if it were, then there would have to be both electric and magnetic fields present in every system, which is obviously false - take for example the case of a single stationary point charge).

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  • $\begingroup$ Thank you. And so for a point charge the electric field lines are not comparable with the electric field vectors of a typical time-dependent electromagnetic wave (the vectors that evolve as a sinusoidal function over time)? I mean, it is a completely different representation? $\endgroup$ – MariNala May 29 '17 at 12:25

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