JEE Advanced 2010 Physics question
A large glass slab of thickness 8 cm is placed over a point source of light on a plane surface. It is seen that light emerges out of the top surface of the slab from a circular area of radius R cm. What is the value of R ?
Answer: 6
Solution
Light from the source can leave the top surface only where the angle of incidence there is less than the critical angle C; beyond that it is totally internally reflected. $ C = 1μ
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