Electric field of a plane electromagnetic wave propagating through a non-magnetic medium is given by E = 20 cos 2 × 10 10 t - 200 x V m - 1 . The dielectric constant of the medium is equal to: (Take μ r = 1 )

Step-by-step solution

Equate the wave equation with the equation of EM wave, E = E 0 cos ω t - k x   V   m - 1 here the given equation of EM wave, E = 20 cos 2 × 10 10 t - 200 x   V   m - 1 ⇒ v = ω k = 2 × 10 10 200 = 10 8   m   s - 1 The refractive index, ⇒ n = c v = 3 × 10 8 10 8 ⇒ 3 = μ r ε r    μ r = 1 given ) ε r = 9