Speed of electromagnetic wave in a medium having relative permittivity _r and relative permeability _r is (speed of light in air, .c=3 10^8 ~m / s )

Step-by-step solution

The speed of an electromagnetic wave in a vacuum is given by c = 1 ₀ ₀ . The speed of an electromagnetic wave in a medium with absolute permittivity and absolute permeability is given by v = 1 . The absolute permittivity and permeability are related to their relative values by = ₀ _r and = ₀ _r . Substituting these into the expression for v , we get v = 1 ( ₀ _r)( ₀ _r) = 1 ₀ ₀ _r _r . Since c = 1 ₀ ₀ , the expression becomes v = c _r _r . Answer: c _r _r