Electromagnetic waves travel in a medium with a speed of 2 × 10 8 m s − 1 . The relative permeability of the medium is 1 . Find the relative permittivity.

Step-by-step solution

Here, v = 2 × 10 8 m s − 1 and μ r = 1 The speed of electromagnetic waves in a medium is given by v = 1 μ ε , ....(i) where μ and ε are absolute permeability and absolute permittivity of the medium. Now, μ = μ 0 μ r and ε = ε 0 ε r Therefore, the equation (i) becomes v = 1 μ 0 μ r × ε 0 ε r = 1 μ 0 ε 0 × 1 μ r ε r = c μ r ε r or ε r = c 2 v 2 μ r = 3 × 10 8 2 2 × 10 8 2 × 1 = 2.25