Question

Light is made incident from glass to air. What is the critical angle for the glass if the refractive index of glass is 1.50 and the refractive index of air is 1.00?

Answer 1

Given data:

refractive index of glass (n₁) = 1.50 ,

refractive index of air (n₂) = 1.00,

determine the critical angle of the glass (θₙ) = ?

Critical angle is defined as "it is the incidence angle, beyond which total internal reflection will occurs".

According to snell's law critical angle is given by the equation

Assume light travels from higher refractive index (glass) to lower refractive index (air)

Critical angle,  

                                  sin θc =  (n₂/n₁)            n₁ > n₂

                                        θc =  sin ⁻¹(1.00/1.50)

                                       θc  = 41.8⁰

The critical angle of the glass is 41.8⁰