question_answer

Light is incident from a medium into air at two possible angles of incidence \[{{20}^{0}}\] and \[{{40}^{0}}\] In the medium light travels 3.0 cm in 0.2ns. The ray will:    [JEE ONLINE 09-04-2013]

A)             suffer total internal reflection in both cases [a] and [b]

B)             suffer total internal reflection in cases [b] only

C)             have partial reflection and partial transmission in case [b]

D)             have 100% transmission in case [a]

Correct Answer: B

Solution :

[b] Refractive index

From total internal reflection

So,

For total internal reflection

So for second case, total internal reflection is possible.