Basic Refraction question. Kindly help

[helpphysics]

Homework Statement

A fisherman in a stream 20 cm deep looks downward into the water of stream
and sees a rock on the stream bed.
How deep does the stream appear to the fisherman?

Homework Equations

We Assume that the index of refraction of the water is 1.33.

The Attempt at a Solution

I am not able to apply the normal angle equation here..nuts !

 

[helpphysics]

Kindly let me know the formula concept and i will calculate myself. I am really not getting it.
Thanks in advance

 

[Stonebridge]

The formula is derived according to the following theory.
It's a method for measuring refractive index using apparent depth, but you can apply it to your problem quite easily.

 

[helpphysics]

Thanks mate. You really explained me the concept behind it too
Thanks once again. yoyo !

 

[rdl]

The depth of the stream as it appears to the fisherman will be different from the actual depth of 20 cm due to refraction. Refraction is the bending of light as it passes from one medium to another with a different density. In this case, the light is passing from air to water, which has a higher density, causing the light to bend towards the normal line (the line perpendicular to the surface of the water).

To calculate the apparent depth of the stream, we can use the equation:

Apparent depth = Actual depth / Refractive index

In this case, the refractive index is 1.33 (given in the problem). Therefore, the apparent depth of the stream would be:

Apparent depth = 20 cm / 1.33 = 15.04 cm

This means that the stream would appear to be 15.04 cm deep to the fisherman, even though it is actually 20 cm deep. This is due to the bending of light as it passes from air to water.