Light rays from a source are incident on a glass prism of index of refraction \mu and angle of prism of. At near normal incidence, calculate the angle of deviation of the emerging rays.

At near normal incline Since $r_1+r_2=A$

Since $r_1+r_2\Rightarrow r_2=\alpha$

From Snell's Law applied at the face from where the refracted ray emerges, we get

$$\begin{gathered} \mu =\frac{\sin e}{\sin r_2} \\ \Rightarrow e={\sin }^{-1}\left(\mu \sin \alpha \right) \end{gathered}$$

Now, deviation$\delta =i+e-A={\sin }^{-1}\left(\mu \sin \alpha \right)-a$

$\Rightarrow \delta ={\sin }^{-1}\left(\mu \sin \alpha \right)-\alpha$