The refractive index and the permeability of a medium are respectively 1.5 and 5 × 10⁻⁷Hm⁻¹. The relative permittivity of the medium is nearly

6

Given refractive index

$ n = 1.5$

Permeability $\mu_0 = 5 × 10^{-7}$

$ n = \sqrt{\mu_r ε_r}$

$ ε_r =\frac{n^2}{\mu_r}$

or $ ρ = \frac{n^2 \mu_0}{\mu}$      $(∵\mu_r = \frac{\mu}{\mu_0})$

or $ ε_r =\frac{(1.5)^2×4\pi ×10^{-7}}{5 × 10^{-7}}$

or $ ε_r = 6 $