A ray of light enters a spherical drop of a liquid of refractive index $\mu =\frac{\sqrt{7}}{2}$. This ray after getting reflected from back surface comes out as shown. Given $\sin {41}^0=\sqrt{\frac{3}{7}}$

 

Total deviation suffered by ray (Refraction + Reflection + Refraction) is minimum
when $\varphi ={60}^0$

When angle of incidence is chosen such that total deviation is minimum, then value of
total deviation is 136⁰ .

Ray suffers total internal reflection at back surface.

Total internal reflection at back surface is not possible for any value of $\varphi$