The ratio of the thickness of plates of two transparent mediums $A$ and $B$ is $6 : 4$. If light takes equal time in passing through them,then the refractive index of $B$ with respect to $A$ will be:

Shown in the figure is a transparent tank of length $30 \,cm$. $A$ black strip of width $3.8 \,cm$ is stuck on its left wall. When a source of light is kept to the left of it,a shadow of width $7.6 \,cm$ is formed on the right wall. Now,the tank is filled with a liquid of refractive index $n$,and the width of the shadow reduces to $6.4 \,cm$. The value of $n$ is closest to

$A$ ray of light is incident on a transparent sphere at an angle of $\pi / 4$ and is refracted at an angle $r$. The ray emerges from the sphere after suffering one internal reflection. The total angle of deviation of the ray is

The speed of light in air is $3 \times 10^8 \, m/s$. What will be its speed in diamond,whose refractive index is $2.4$?

Light of wavelength $300 \ nm$ in medium $A$ enters into medium $B$ through a plane surface. If the frequency of light is $5 \times 10^{14} \ Hz$ and the ratio of speed in medium $A$ to that in medium $B$ is $\frac{4}{5}$,the absolute refractive index of medium $B$ is:

When light travels from one medium to another with a different refractive index, which of the following will change?