An opaque cylindrical tank with an open top has a diameter of `3.00m` and is completely filled with water .When the setting sun reaches an angle of `37^(@)` above the horizon,sunlight ceases to illuminate any part of the bottom of the tank .How deep is the tank?

Options

A. 3 m
B. 4 m
C. 5 m
D. Not possible

Answer

B

Explanation

By Snell's law, 1 ` sin 53^@ = ( 4 ) /( 3) sin r, ( 4 ) /( 5 ) = ( 4 ) / ( 3 ) sin r, sin r = ( 3 ) /( 5 ) rArr r = 37^@ `
In ` Delta OAB, tan r = ( 3 ) /(H) = tan 37^@ rArr H = 4 ` metres