For a thin symmetric prism of refractive index 1.5, what is the ratio of the angle of incidence i at minimum deviation to the minimum deviation δₘ?
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Question

For a thin symmetric prism of refractive index 1.5, what is the ratio of the angle of incidence i at minimum deviation to the minimum deviation δₘ?

G1 Physics · Accepted Answer

For a thin prism, δₘ = (μ-1)A. With μ = 1.5, δₘ = (1.5-1)A = A ÷ 2. At minimum deviation, i = (A+δₘ) ÷ 2. Therefore, i = [A+A ÷ 2] ÷ 2 = (3A ÷ 2) ÷ 2 = 3A ÷ 4. Hence, i:δₘ = (3A ÷ 4):(A ÷ 2) = 3:2. Correct option: B.