A tank is filled with water to a height of 15 cm. If the refractive index of water is 1.33, the apparent depth of a needle lying at the bottom of the tank will be

11.28 cm

The correct answer is Option (1) → 11.28 cm

Real depth = 15 cm

Refractive index: $ \mu = \frac{\text{Real depth}}{\text{Apparent depth}} $

$ \text{Apparent depth} = \frac{\text{Real depth}}{\mu} = \frac{15}{1.33} \approx 11.28 \, \text{cm} $

Answer: $ \; 11.3 \, \text{cm (approx.)} $