Write the conditions for total internal reflection.

$A$ ray of light is incident at an angle $i$ from a denser to a rarer medium. The reflected and the refracted rays are mutually perpendicular. The angle of reflection is $r$ and the angle of refraction is $r'$. Then the critical angle $C$ will be:

What is total internal reflection?

$A$ 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 $B$?

When a ray is refracted from one medium to another,the wavelength changes from $6000 \, \mathring A$ to $4000 \, \mathring A$. The critical angle for the interface will be

The critical angle of light going from medium $A$ to medium $B$ is $\theta$. The speed of light in medium $A$ is $v$. The speed of light in medium $B$ is: