Problem

The apparent depth of water in cylindrical water tank of diameter

2R

cm is reducing at the rate of

x

cm/min when water is being drained out at a constant rate. The amount of water drained in cc/min is (

n_1

= refractive index of air,

n_2

= refractive index of water) a.

\frac{x\pi R^2 n_1}{n_2}

\frac{x\pi R^2 n_2}{n_1}

\frac{2\pi R n_1}{n_2}

\pi R^2 x