Light is incident from glass ( μ = 1.5 ) to air. Which of the...

For $i < i_c$, refraction takes place.

By Snell's law, $\mu \sin i = 1 \cdot \sin r \Rightarrow r = \sin^{-1}(\mu \sin i)$

The angle of deviation is $\delta = r - i = \sin^{-1}(\mu \sin i) - i$

This shows that $\delta$ increases non-linearly with $i$ for $i < i_c$.

At $i = i_c$, the angle of refraction is r = 90^{}^{{}^{\circ}}.

The deviation is \delta_1 = 90^{}^{{}^{\circ}} - i_c.

For $i > i_c$, total internal reflection takes place.

The angle of deviation for reflection is \delta = 180^{}^{{}^{\circ}} - 2i.

This shows that $\delta$ decreases linearly with $i$ for $i > i_c$.

Just after the critical angle, as $i \to i_c$, the deviation due to total internal reflection is \delta_2 = 180^{}^{{}^{\circ}} - 2i_c.

Since $\delta_2 \neq \delta_1$, there is a discontinuous jump in the angle of deviation at $i = i_c$.

Therefore, $\delta$ increases non-linearly for $i < i_c$, jumps discontinuously at $i = i_c$, and decreases linearly for $i > i_c$.