What is the fundamental difference between the process of propagation of an electromagnetic wave in space from the process of propagation of mechanical vibrations in an elastic medium? What is called: a) an electromagnetic wave; b) a harmonic electromagnetic wave?
For the propagation of elastic waves, an elastic medium is required. On the contrary, an electromagnetic wave is capable of propagating in space where there is no substance, that is, in a vacuum. This is due to the fact that in an electromagnetic wave, oscillations are performed not by particles of matter, but by vectors in the intensity and magnetic induction of periodically changing electric and magnetic fields. An alternating electromagnetic field propagating in space is called an electromagnetic wave. The simplest model of an electromagnetic wave is a harmonic electromagnetic wave, which is an infinite sinusoidal wave.
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