Question

A coin placed at the bottom of a 2 litre beaker filled with water appears raised by 6 cm. If the refractive index of water is `4/3`, find the depth of water in the beaker.

Answer 1

Let the real depth of the water be d cm. Since the coin appears raised by 6 cm, its apparent depth is (d − 6) cm.

\[ \text{Refractive index of water} = \frac{\text{Real depth}}{\text{Apparent depth}} \]

\[ \frac{4}{3} = \frac{d}{d - 6} \]

\[ 4(d - 6) = 3d \]

4d − 24 = 3d

d = 24 cm

Therefore, the depth of water is 24 cm. The beaker’s capacity is not needed for this calculation.