A person at height 10 m stands on the bank of a 50 m wide river. A 40 m tower is on the opposite bank. Light reflected from the water is observed through a polarizer and has minimum intensity at a reflection point distance X from the person. The corresponding source on the tower is at height Y. For water refractive index 4/3, find X and Y.

Question

G1 Physics · Accepted Answer

At Brewster incidence tan i=4/3. If the reflection point is X from the observer bank, X/10=4/3 gives X≈13.3 m. The remaining horizontal distance is 50-X≈36.7 m, and (50-X)/Y=4/3 gives Y≈27.5 m. Closest option: 13 m, 27 m. Option A.