Question

Deduce an expression for velocity of em waves in vacuum 2

Answer 1

is the speed of light (i.e. phasevelocity) in a medium with permeability μ, and permittivity ε, and ∇2 is the Laplace operator. In avacuum, vph = c0 = 299,792,458 meters per second, a fundamental physical constant. The electromagnetic wave equation derives from Maxwell's equations.