Chapter 23, Problem 12Q

You look into an aquarium and view a fish inside. One ray of the light from the fish is shown emerging from the tank in Fig. 23-48. The apparent position of the fish is also shown (dashed ray). In the drawing, indicate the approximate position of the actual fish. Briefly justify your answer.

To determine

The approximate position of the actual fish in a tank in an aquarium and it is given in the figure below that one ray of light from the fish is shown emerging from the tank and the apparent position of the fish is also shown (dashed ray).

Answer to Problem 12Q

Solution:

The approximate position of the real fish in the tank is below the apparent position of the fish that is seen by the person. This can be shown by the following diagram.

Explanation of Solution

The apparent position of the fish in a tank is shown (dashed ray). The fish in the aquarium is viewed by a person and to his vision through the glass tank; the apparent position of the fish can be viewed.

The light ray from the fish is travelling in the water and bent away from the normal as they exit the wall of the tank due to the refraction.

These refracted rays are viewed by an observer and his brain interprets that the rays appear to come from the position above the position of the real fish. Also, the image appears to be slightly closer to the wall of the aquarium. Since the brain doesn’t know that light bends at the water/air interface, when the brain “follows” the ray back into the tank, it interprets the location of the fish as above its actual location.