Physics Help Forum refraction at plane surface

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 Jun 29th 2009, 04:12 PM #1 Junior Member     Join Date: Jun 2009 Posts: 11 refraction at plane surface A fish looking up through water sees the outside world contained in a circular horizon.If refractive index of water is 4/3 & the fish is 12cm below the surface, the radius of this circle in cm is? i have tried this question but could not visualize the questio thus was not able to solve the question any help would be grateful
Jun 29th 2009, 06:16 PM   #2
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 Originally Posted by abhishek arora A fish looking up through water sees the outside world contained in a circular horizon.If refractive index of water is 4/3 & the fish is 12cm below the surface, the radius of this circle in cm is? i have tried this question but could not visualize the questio thus was not able to solve the question any help would be grateful
In almost all text books you can see this problem.
First find the critical angle of he water. What is the relation between critical angle and refractive index?
Draw the diagram indicating the position of the fish and circular patch of light.
From the diagram you can see that R/H = tanC

 Jun 29th 2009, 06:27 PM #3 Junior Member     Join Date: Jun 2009 Posts: 11 query why we consider the critical angle this is my main query how do we know that light enters at critical angle and even it enters i suppose for 1 moment can believe but how could we say that ray must reach the fish's eye Last edited by abhishek arora; Jun 29th 2009 at 06:29 PM.
Jun 29th 2009, 06:39 PM   #4
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 Originally Posted by abhishek arora why we consider the critical angle this is my main query how do we know that light enters at critical angle and even it enters i suppose for 1 moment can believe but how could we say that ray must reach the fish's eye
On any denser medium angle of incidence will very from zero to 90 degrees.
Then what is the range of the angle of refraction in the denser medium?

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### a fish is looking through water sees the outside world contained in a sphere. Find radius of sphere

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