The critical angle of a medium for a specific wavelength, if the medium has relative permittivity 3 and relative permeability $\frac{4}{3}$ for this wavelength, will be:

30°

The correct answer is Option (2) → 30°

The refractive index of a material ($μ$) is -

$μ=\sqrt{ε_rμ_r}$

$=\sqrt{3.\frac{4}{3}}=\sqrt{4}=2$

and,

Critical Angle, $θ_c$ is -

$\sin θ_c=\frac{1}{n}$

$θ_c=\sin^{-1}\left(\frac{1}{2}\right)=30°$