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,
$\delta =\pi -2i$
$=180^{\circ }-2\times 65^{\circ }=50^{\circ }$