It is found that electromagnetic signals sent inside a glass sphere from $A$ towards $B$ reach point $C$. The speed of electromagnetic signals in glass cannot be:

At what angle of incidence should a ray be incident on a glass sphere of refractive index $3/2$ so that the ray does not emerge from the sphere?

$A$ jar of height $h$ is filled with a transparent liquid of refractive index $\mu$. At the centre of the jar on the bottom surface is a dot. Find the minimum diameter of a disc,such that when placed on the top surface symmetrically about the centre,the dot is invisible.

In the figure shown,for an angle of incidence $i$ at the top surface,the minimum refractive index $\mu$ needed for total internal reflection at the vertical surface will be

$A$ rod of glass $(\mu = 1.5)$ with a square cross-section is bent into the shape shown in the figure. $A$ parallel beam of light falls on the plane flat surface $A$ as shown. If $d$ is the width of a side and $R$ is the radius of the inner circular arc,what is the maximum value of $\frac{d}{R}$ such that the light entering the glass slab through surface $A$ emerges from the glass through $B$?

$A$ 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 ....... $^o$.