The apparent depth of water in cylindrical water tank of diameter 2R cm is reducing at the rate of x cm/minute when water drained out at a constant rate. The amount of watr drained in c.c. per minute in (`n_(1)=` refractive index of air `n_(2)=` refractive index of water)

Options

A. `x pi R^(2)n_(1)//n_(2)`
B. `xpiR^(2)n_(2)//n_(1)`
C. `2piRn_(1)//n_(2)`
D. `piR^(2)x`

Answer

B