Question

Explain, how the refractive index of a material is related to the critical angle.

Answer 1

• Critical angle: Angle of incidence in a denser medium, for which the angle of refraction in the rarer medium is $90°$ is called the critical angle.
• The ratio between the sine of the angle of incidence and the sine of the angle of refraction is commonly called the refractive index of the material in which the angle of refraction is situated with respect to the medium in which the angle of incidence is situated.

R.I. is related to critical angle as,

$$\begin{gathered} \text{R.I.}=\frac{1}{\text{sine of critical angle}} \\ \text{R.I.}=\frac{1}{s\mathrm{in}C} \end{gathered}$$