The refractive index and the permeability of a medium are respectively 1.5 and  $10\times {10}^{-7}H{m}^{-1}$. The relative permittivity of the medium is nearly ____

Refractive index,  $n=\frac{C}{V}$
Velocity of wave in medium,  $V=\frac{C}{n}=\frac{3\times {10}^8}{3/2}=2\times {10}^8\frac{m}{s}$
Here  $\mu =10\times {10}^{-7}H{m}^{-1}$
Velocity of wave ,  $V=\frac{1}{\sqrt{\mu \in }}=\frac{1}{\sqrt{\mu {\in }_0{\in }_r}}$
$\Rightarrow {\in }_r=\frac{1}{V^2\mu {\in }_0}=\frac{1}{{(2\times {10}^8)}^2\times 10\times {10}^{-7}\times 8.85\times {10}^{-12}}$ 
 $\Rightarrow {\in }_r=2.82$