A large glass slab ( μ = 3 5 ) 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 r

Question

A large glass slab ( μ = 3 5 ​ ) 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 ?

TestHub · Accepted Answer

t R ​ = tan θ C ​ or R = t ( tan θ C ​ ) ​ But, sin θ C ​ = μ 1 ​ = 5 3 ​ ∴ tan θ C ​ = 4 3 ​ ∴ R = 4 3 ​ t = 4 3 ​ ( 8 cm ) = 6 cm ​ Hence the answer is 6 .

Physics - Geometrical Optics Question with Solution | TestHub

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