question_answer

When a ray of light is incident normally on refracting surface of an equilateral prism: (Refractive index of the material of the prism =1.5)

A)  emerging ray is deviated by \[30{}^\circ \]

B)  emerging ray is deviated by \[45{}^\circ \]

C)  emerging ray just grazes second refracting surface

D)  the ray undergoes  total  internal reflection at the second refracting surface

Correct Answer: D

Solution :

                 The ray of light incidents normally. So,    \[\angle {{i}_{1}}=0\] and \[\angle {{r}_{1}}=0\] But   \[\angle {{r}_{1}}=0,\angle {{r}_{2}}={{60}^{o}}\] So, the ray will suffer total internal reflection of light.