Question

To what height water should be filled in a container of height 21 cm, so that it appears as half filled when viewed from the top? $(Take{}_a{\mu }_w=\frac{4}{3})$

• A. 12 cm
• B. 15 cm
• C. 10.5 cm
• D. 7 cm

Answer 1

The correct option is A 12 cm

Let the water should be filled up to height $x$, so that bottom of the container should appear to be raised up to height $(21-x)$.

Apparent depth (from figure) $h^{\prime }=(21-x)$

Real depth, $h=x$

$\therefore \mu =\frac{h}{h^{\prime }}$

$\frac{4}{3}=\frac{x}{21-x}$

$x=12cm$