# Fish Apparent Position Using Refraction in Water

• physicsmaths1613
In summary, the question asks for the apparent position of a fish under water when viewed by a bird directly overhead. This is solved using the principles of refraction, as the light rays passing through the water and air cause the fish to appear closer to the surface than its actual position.

## Homework Statement

A fish is 60 cm under water. A bird directly overhead looks at the fish. If the bird is 120 cm above the water level, find the apparent position of the fish as seen by the bird.

The question is solved by using the principles of refraction. But, if the bird is directly overhead, there should be no bending of the light rays. Then why do we use refraction here?

Hi pm1613:

I suggest that you consider how far underwater the fish appears to be from the perspective of the bird.

Regards,
Buzz

physicsmaths1613 said:

## Homework Statement

A fish is 60 cm under water. A bird directly overhead looks at the fish. If the bird is 120 cm above the water level, find the apparent position of the fish as seen by the bird.

The question is solved by using the principles of refraction. But, if the bird is directly overhead, there should be no bending of the light rays. Then why do we use refraction here?
From a given point on an object being viewed, light rays go out in all directions. Some of these fall on the lens of your eye, and are brought back together by the lens to focus on your retina. If, along the way, they pass from water into air, they will diverge a little at that boundary. If you project the diverged lines back under water, they will meet at a point closer to the surface than the actual object. That is where you will perceive the object to be.