HC Verma - Concepts of Physics Part 1

Book: HC Verma - Concepts of Physics Part 1

Chapter: 18. Geometrical Optics

Subject: Physics - Class 12th

Q. No. 32 of Exercises

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32

A point source is placed at a depth h below the surface of water (refractive index = μ).

(a) Show that light escapes through a circular area on the water surface with its center directly above the point source.


(b) Find the angle subtended by a radius of the area on the source.


(a) Let x= radius of the circular area


32.PNG


S be the point source


H is the depth


Critical angle=


So,



(since,)




So, clearly from the fig., light escapes from the circular area at a fixed desistance r on the water surface, directly above the point source S.


(b) The angle subtended by a radius of the area on the source S




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