Question

In words, how do you derive the electromagnetic wave equation? Does it contain the phase or group velocity?

Answer 1

Electromagnetic wave equation is a second order partial differential equation which describe the propagation of wave in terms of electric field and magnetic field so first we have to derive the electric field and magnetic field and after that we have to find the relation between them we have to introduce another vector for electric field and magnetic field separately due to which new Maxwell equations form can be obtained.

As the electromagnetic wave equation describe the propagation of wave so it will depend on the propagation vector 2 therefore we can say that there also be a incubation of director ke as well as group velocity and phase velocity inside the brave equation in different types of forms of the equation.