$A$ 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

When a glass prism of refracting angle $60^{\circ}$ is immersed in a liquid, its angle of minimum deviation is $30^{\circ}$. The critical angle of glass with respect to the liquid medium is (in $^{\circ}$)

For the angle of minimum deviation of a prism to be equal to its refracting angle,the prism must be made of a material whose refractive index

An isosceles prism of angle $A=30^{\circ}$ has one of its surfaces silvered. Light rays falling at an angle of incidence $60^{\circ}$ on the other surface retrace their path after reflection from the silvered surface. The refractive index of the prism material is

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?

$A$ prism of angle $A=1^{\circ}$ has a refractive index $\mu=1.5$. $A$ good estimate for the minimum angle of deviation (in degrees) is close to $N/10$. The value of $N$ is......