Question

How is the refractive index of a material related to real and apparent depth?

Answer 1

Consider a coin is placed at the bottom of the swimming pool having a depth $D$ and filled with water of refractive index $n$.

When we see that coin from outside the pool, it is appeared to be at a depth which is less than the real depth of the pool. This appeared depth is said to be apparent depth.

Apparent depth is related to the refractive index and real depth by the following relation-

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