Question

A ray of light passing from glass to water is incident on the glass-water interface at $65^{\circ}$. If the critical angle for the pair of media is $63^{\circ}$,

• A. The ray will emerge into water with a deviation of $2^{\circ}$ from the normal
• B. The ray will be refracted into water with a deviation of $2^{\circ}$
• C. The ray will be totally internally reflected back into glass with a deviation of $50^{\circ}$
• D. The ray will be totally internally reflected back in glass with a deviation of $2^{\circ}$

Answer 1

Answer: (C)

Here, critical angle, $\theta, = 63^{\circ}$
Angle of incidence, $i = 65^{\circ}$
Since the light is incident at an angle $i > \theta_c,$ then angle of deviation is given by,
$ \delta = \pi - 2i$
$ \, \, \, \, = 180^{\circ} - 2 \times 65^{\circ} = 50^{\circ}$