Originally Posted by **DesertFox** Euler's number...... the well-known mathematical constant. The number is related to every natural growth process....
But the what is the exact meaning of Euler's number in electromagnetism? How exactly it is used in electromagnetism? And how come it is so necessary? |

Why are you saying that its so necessary? In what context are you referring to it being used?

e is the base of the natural logarithm I believe it appears when analyzing the decrease in the amplitude of an EM wave when it enters a material.

Also, all EM waves can be described using sinusoidal waves (e.g. in terms of Fourier integrals of Fourier series) which use the sine and cosine functions. Those functions can be written in terms of e by using Euler's formula: See:

https://en.wikipedia.org/wiki/Euler%27s_formula
It can make the math easier when expressed in terms of e.