Question

In the figure shown, what is the apparent distance of the fish as seen by the bird ?

• A. $27\text{m}$
• B. $30\text{m}$
• C. $63\text{m}$
• D. $72\text{m}$

Answer 1

The correct option is C $63\text{m}$

Given: height of bird above water $h=36\text{m}$
depth of fish below water $d=36\text{m}$

Here, bird is an observer that means light rays are coming from the fish and falling on the bird's eyes.

So, ${\mu }_1=4/3;{\mu }_2=1.$

So, using formula of apparent depth
$\frac{d^{\prime }}{d}=\frac{{\mu }_2}{{\mu }_1}$

$\Rightarrow d^{\prime }=36\times \frac{3}{4}=27\text{m}$

So, apparent distance of fish as seen by the bird $=(36+27)\text{m}=63\text{m}$.

Hence, option $\left(c\right)$ is the correct answer.