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

$A$ fish is a little below the surface of a lake. If the critical angle is $49^\circ$,then the fish could see things above the water surface within an angular range of $\theta^\circ$ where

$A$ ray of light originates from inside a glass slab and is incident on its inner surface at an angle $\theta$ as shown below. In this experiment,the location $x$ of the spot where the ray hits the screen is recorded. Which of the following correctly shows the plot of variation of $x$ with the angle $\theta$?

It is found that all electromagnetic signals sent from $A$ towards $B$ reach point $C$. The speed of electromagnetic signals in glass can not be

$A$ diver at a depth of $12 \ m$ in water $\left(\mu = \frac{4}{3}\right)$ sees the sky in a cone of semi-vertical angle:

Total internal reflection is possible when light rays travel: