$A$ point source of light is placed $4 \, cm$ below the surface of water with a refractive index of $\mu = 5/3$. What is the minimum diameter of a disc that should be placed over the source to stop all light from coming out of the water? (in $m$)

The reason for the shining of an air bubble in water is

$A$ right-angled glass prism is shown in the figure. $A$ liquid film is in contact with the hypotenuse face. $A$ ray of light incident normally on the face $AB$ will undergo total internal reflection from the hypotenuse face,if the refractive index of the liquid is $\mu_l$ (given $\mu_{\text{glass}} = 3/2$).

The relation between the critical angles of water and glass is:

$A$ point source $S$ is placed at the bottom of different layers as shown in the figure. The refractive index of the bottom-most layer is $\mu_0$. The refractive index of any other upper layer is $\mu(n) = \mu_0 - \frac{\mu_0}{4n - 18}$,where $n = 1, 2, \dots$. $A$ ray of light with an angle of incidence $i$ slightly more than $30^\circ$ starts from the source $S$. Total internal reflection takes place at the upper surface of a layer having $n$ equal to

In the given figure,at the water-air interface,a light ray is incident at the critical angle. Find the value of $\mu_g$.