A placed bulb is placed at the bottom of a tank containing water to a depth of 80 cm. What is the area of the surface of water through which light from the bulb can emerge out ? Refractive index of water is 1.33 consider the bulb to be a point source .

Question

$\begin{array}{1 1} 25.18\;m^2 \\ 2.518\;m^2 \\ 2.518\;cm^2 \\ 25.18\;cm^2 \end{array} $