The bottom of a container is a 6 cm thick glass $(μ=1.5)$ slab. The container contains a thick layer of water $(μ_w=1.33)$, 4 cm on top of the glass. What is the apparent position of a scratch on the outer surface of the bottom of the glass slab when viewed through the container?

3 cm

The correct answer is Option (4) → 3 cm

When light passes through water, it bends due to the difference in refractive indices between air and water.

$d_{apparent}=\frac{d_{actual}}{μ}=\frac{4}{1.33}≃3.00cm$