A straight stick of length is held vertically in a swimming pool so that its lower…
PHYSICS · Multi-part · CBSE · Physics · Light — Reflection and Refraction · Light — Reflection and Refraction
Problem
A straight stick of length 1.2m is held vertically in a swimming pool so that its lower end is 0.80m below the water surface. The refractive index of water with respect to air is 34. Answer the following.
(i) Derive an expression for the apparent depth of a point situated at a real depth h below a plane water surface as seen by an observer in air looking vertically downward.
(ii) Using your result from part (i), calculate the apparent position of the lower end of the stick below the water surface.
(iii) Hence determine the apparent length of the portion of the stick that lies inside the water.
(iv) Explain qualitatively why the stick appears bent or displaced at the water surface even though it is perfectly straight.