$A$ ray of light travels from a medium of refractive index $2$ to another medium of refractive index $\sqrt{2}$. Total internal reflection takes place when the angle of incidence is

$A$ point source of light $S$ is placed at the bottom of a vessel containing a liquid of refractive index $\mu = 5/3$. $A$ person is viewing the source from above the surface. There is an opaque disc $D$ of radius $r = 1\, cm$ floating on the surface of the liquid. The centre of the disc lies vertically above the source $S$. The liquid from the vessel is gradually drained out through a tap. The maximum height $h$ of the liquid for which the source cannot be seen at all from above is: (in $, cm$)

Calculate the critical angle for a glass-air surface,if a ray of light incident in air on the glass surface is deviated by $15^{\circ}$ when the angle of incidence is $45^{\circ}$. (in $^{\circ}$)

$A$ light ray falls on a glass surface of refractive index $\sqrt{3}$,at an angle of $60^{\circ}$. The angle between the refracted and reflected rays would be ....... $^o$.

The critical angle for light going from medium $A$ into medium $B$ is $\theta$. The speed of light in medium $A$ is $V_A$. What is the speed of light in medium $B$?

$A$ ray is incident from a medium of refractive index $2$ into a medium of refractive index $1$. The critical angle is (in $^{\circ}$)