Fish eye view through water surface · BPhO 2008 #5
Physics · optics
Problem
A fish floats in water with its eye at the centre of an opaque walled full tank of water of circular cross section. When the fish look upwards, it can see a fish-eye view of the surrounding scene i.e. it is able to view the hemisphere of the scene above the water surface, and centred at the top of the tank. The diameter of the tank is 30 cm, and the critical angle for water is 48°. At what depth below the surface of the water, d, must the fish be floating?
[Figure: Diagram showing circular tank with fish at depth d below water surface]
A. 16.7 cm
B. 13.5 cm
C. 11.2 cm
D. 10.0 cm