Question

A fish swims 20 cm from the front wall of an aquarium that is 35cm wide. The front wall of the aquarium is glass with negligible thickness, but the back wall is a plane mirror. A person looks through the front wall and watches both the fish and its reflection in the mirror.

Part A What is the apparent distance from the front wall of the aquarium to the fish? nothing cm SubmitRequest Answer Part B What is the apparent distance from the front wall of the aquarium to the image of the fish in the mirror?

Answer 1

a) Real distance from the front wall of to the fish is dr = 20 cm

The apparent distance is da = dr/n

where n = 1.33 is the refractive index of water

Therefore the apparent distance from the front wall of the aquarium to the fish is

da = 20/1.33 = 15 cm

b) Distance between fish and mirror is 35 - 20 = 15 cm

Real distance from the front wall of to the image of fish is dr = 35 +15 = 50 cm

The apparent distance is da = dr/n

where n = 1.33 is the refractive index of water

Therefore the apparent distance from the front wall of the aquarium to the image of the fish is

da = 50 / 1.33 = 37.5 cm