# Refraction in water

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1. Jun 10, 2016

### physicsmaths1613

1. The problem statement, all variables and given/known data
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?

2. Jun 10, 2016

### Buzz Bloom

Hi pm1613:

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

Regards,
Buzz

3. Jun 11, 2016

### haruspex

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.

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