A ray of light is incident on a glass sphere of refractive index 3/2. What should be the angle of incidence in degrees so that the ray that enters the sphere does not come out of the sphere?
∠ABO=∠OAB=θC
sinθC=1μ=23
Applying Snell's law at A
sinisinθc=32
sini=(32)(23)=1
or i = 90
Ans : 90∘
Why this question? Note: When a ray passes from an optically denser medium to an optically rarer medium, for a certian angle of incidence, there is no refraction and the ray undergoes total internal reflection. We call such angle of incidence as critical angle. |