A light ray moving in medium-I (of refractive index `n_(1)`) is incident on interface of two media and it is totally internally reflected at the interface. Now, refractive index `n_(2)` of medium-II is decreased, then

Options

A. ray will move completely parallel to the interface
B. ray will be still totally internally reflected at interface
C. ray will be totally transmitted into medium-II only, if angle of incidence is increased
D. ray will be totally transmitted in medium-II

Answer

B

Explanation

As `n _(2)` decreases, `i _(c) = sin ^(-1) (( n _(2))/( n _(1)) )` also decreases.
So, condition `I gt I _(C)` is still satisfied and there will be still total internal reflection at interface. If angle of incidence is increased, then ray will be still totally internally reflected at interface because `i gt i _(C).`