A coin is placed at the bottom of a pond of real depth

PHYSICS · Subjective · CBSE · Physics · Light — Reflection and Refraction · Light — Reflection and Refraction

Problem

D

. (a) Draw a neat ray diagram to show how the coin appears at a smaller depth

d

to an observer looking vertically downward from air. (b) Using geometrical reasoning, derive the relation

n = \dfrac{D}{d}

, where

n

is the refractive index of the pond water with respect to air. (c) In a particular case the real depth of the coin is

12\,\text{cm}

while its apparent depth is

9\,\text{cm}

. Calculate the refractive index of the water. (d) The pond is now filled with another transparent liquid to the same depth of

12\,\text{cm}

. The coin now appears at a depth of

8\,\text{cm}

. Determine the refractive index of this liquid and state whether it is optically denser or rarer than water.