a
\((a)\)The ray of light is refracted at the plane surface. However, since the ray is travelling from a denser to a rarer medium, for an angle of incidence \((i)\) greater then the critical angle \((c)\) the ray will be totally internally reflected.

\((1)\) For \(i < c\); deviation  = \(r -i\) with \(\frac{1}{\mu } = \frac{{\sin i}}{{\sin r}}\)

Hence \(\delta = {\sin ^{ - 1}}\left({\mu \sin i} \right) - i\)

This is a non-linear relation. The maximum value of

\(\delta\) is \({\delta _1} = \frac{\pi }{2} - c\); where \( i = c\) and \(\mu = \frac{1}{{\sin c}}\)

\((2)\)  For \(i > c\), deviation \(\delta\) = \(\pi\) -\(2i\) 

\(\delta\) decreases linearly with \(i\)

\(\delta_2=\pi -2 c= 2 \delta_1\)