How much water should be filled in a container of height `21 cm,` so that it appears half filled to the observer when viewed from the top of the container `(mu=4//3).`

Options

A. `8.0 cm`
B. `10.5 cm`
C. `12.0 cm`
D. None of the above

Answer

C

Explanation

To see the container half-filled from top, water should be filled up to height `x` so that bottom of the container should appear to be raised upto height `(21-x)`. As shown in figure apparent depth`h^(')=(21-x)`
Real depth `h=x`
`:. mu=(h)/(h^('))implies(4)/(3)=(x)/(21-x)impliesx=12 cm`