Question

A small bulb is placed at the bottom of a tank, containing a transparent liquid of refractive index \(\sqrt{2}\), to a depth of \(1\,\text{m}\). Calculate the area of the surface of the liquid through which light from the bulb emerges.

Hint:

For such total internal reflection problems, \[ r=h\tan C \] and \[ A=\pi r^2. \] Always calculate the critical angle first and then determine the radius of the illuminated circular region.

Answer 1