A light ray is incident perpendicular to one face of a `90^@` prism and is totally internally reflected at the glass-air interface. If the angle of reflection is `45^@`, we conculde that for the refractive index n as

Options

A. `n lt (1)/(sqrt(2))`
B. ` n gt sqr(2)`
C. `n gt (1)/(sqrt(2))`
D. `n lt sqrt(2)`

Answer

B

Explanation

As ray AB is incident at an angle of `45^(@)` and for this ray to suffer total internal reflection.

Here `45^(@) gt theat_(C) implies "sin"45^(@) gt "sin"theta_(C)`
`implies (1)/(sqrt(2)) gt (1)/(n) implies n gt sqrt(2)`