Question

A point object is $24cm$ above the surface of water ( $\mu =4/3)$ in lake. A fish inside the water will observe the image to be at a point:

• A. 6 cm above the surface of water
• B. 6 cm below the surface of water
• C. 18 cm above the .surface of water
• D. 32 cm above the surface of water

Answer 1

Answer: (D)

${}_1{\mu }_2=\frac{\text{ Apparent depth }}{\text{ Real depth }}=\frac{x_{\text{app }}}{x_r}$
Putting the numerical values, we have
$x_r=24cm,{}_1{\mu }_2=\frac{4}{3}$
$\Rightarrow \frac{4}{3}=\frac{x_{app}}{24}$
$\Rightarrow x_{app}=32cm$
Therefore, the object will appear $32cm$ above the surface of the water.