Frequently when EM waves are taught, it is said that the change in electric field causes a change in the magnetic field, which then causes a change in the electric field, and so on and so forth.
But from my understanding of basic electromagnetics, it is not necessarily a changing electric field that creates a change in magnetic field, but instead an accelerating charge. and it is this charge that creates both the electric and magnetic field. Again, from my understanding, a changing magnetic field is not generated by a changing electric field, but instead just happens to always be present perpendicular to a changing electric field due to the laws of electromagnetism.
Am I wrong? Or is the "mutual generation" concept between the electric and magnetic components of an EM wave an actual thing?
Best Answer
As you say, a changing magnetic field is always associated with a changing electric field, and in fact in relativity they are finally revealed to be the same field. So at this level it cannot be said that the one field generates the other, as they are merely two aspects of the same object.
But maybe you still want to look at it from the perspective of "naive EM", and see what sense one could make of the statement that one field generates the other.
Now, if you look at the fields of a plane wave at a fixed point in space, you'll see that they oscillate in sync, and both reach maximum and $0$ intensity at the same time. In fact what you could say is that increasing $E$ field is trying to reduce the $B$ field and the increasing $B$ field is trying to reduce the $E$ field. You could follow the appropriate equations and you'll see this is analogous to the equations of a vibrating membrane.
But the point is, that in fact the fields try to mutually reduce each other rather than generate. In fact they do that so well, that there is an overshoot, and the cycle repeats. This dynamics turns out to make the energy flow through that point in space, to the fields in the neighbouring space. In fact, at some moments there is no EM field at that point, which means there is no energy at that field.
I guess the best description would be that a moving charge generates a disturbance in the electromagnetic field, in the sense that there is an energy transfer from its kinetic energy to the EM energy. This disturbance than propagates through space and time.