The critical angle for light traveling from medium $(i)$ to medium $(ii)$ is $\theta$. If the speed of light in medium $(i)$ is $v$,then the speed of light in medium $(ii)$ is:

$A$ transparent solid cylindrical rod has a refractive index of $\frac{2}{\sqrt{3}}$. It is surrounded by air. $A$ light ray is incident at the mid-point of one end of the rod as shown in the figure. The incident angle $\theta$ for which the light ray grazes along the wall of the rod is

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 $B$?

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

Explain the use of optical fibre in the medical field.

$A$ light ray falls on a square glass slab as shown in the diagram. The index of refraction of the glass,if total internal reflection is to occur at the vertical face,is equal to