A thin prism P₁ with angle 4° and made from a glass of refractive index 1.54 is combined with another thin prism P₂ made from glass of refractive index 1.72 to produce dispersion without deviation. The angle (in degree) of the prism P₂ is :-
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Question

A thin prism P₁ with angle 4° and made from a glass of refractive index 1.54 is combined with another thin prism P₂ made from glass of refractive index 1.72 to produce dispersion without deviation. The angle (in degree) of the prism P₂ is :-

Options

G1 Physics · Accepted Answer

Derived solution: Step 1: For a prism use r₁ + r₂ = A and δ = i + e - A. At minimum deviation i = e and r₁ = r₂ = A/2, so μ = sin[(A + δₘ)/2]/sin(A/2). Step 2: Substitute the values given in the question and apply the geometry/sign convention shown. Step 3: On simplification the result is 3. Therefore the correct option is C.