A light beam is traveling from Region I to Region IV (refer figure). The refractive indices in Regions I, II, III, and IV are n0,n0/2,n0/6, and n0/8, respectively. The angle of incidence θ for which the beam just misses entering Region IV is
A
sin−1(3/4)
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B
sin−1(1/8)
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C
sin−1(1/4)
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D
sin−1(1/3)
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Solution
The correct option is Bsin−1(1/8) by applying snell's law at every interface we get ,
μ1sinα1=μ2sinα2=μ3sinα3...................
so nosinθ=n08sin90 (for just to prevent entering )