If one face of a prism of prism angle $30^{\circ}$ and refractive index $\mu = \sqrt{2}$ is silvered,the incident ray retraces its initial path. The angle of incidence is.......$^{\circ}$

If $r$ and $r^1$ denote the angles of refraction at the two faces of a prism with a prism angle of $50^{\circ}$,and $r$ varies with time $t$ as $r = 10^{\circ} + t^2$,how will $r^1$ vary with time?

The exit surface of a prism with refractive index $n$ is coated with a material having refractive index $\frac{n}{2}$. When this prism is set for minimum angle of deviation, it exactly meets the condition of the critical angle. The prism angle is . . . . . . (in $^{\circ}$)

On which factors does the angle of deviation produced by a prism depend?

$A$ ray of light is incident at $60^{\circ}$ on one face of a prism of angle $30^{\circ}$. The emergent ray makes an angle of $30^{\circ}$ with the incident ray. The refractive index of the prism is

$A$ ray of light is incident normally on a prism of refractive index $1.5$,as shown. The prism is immersed in a liquid of refractive index $\mu$. The largest value of the angle $ACB$ such that the ray is totally internally reflected at the face $AC$ is $30^o$. Then the value of $\mu$ must be :