A ray is incident at angle i on one surface of a small-angle prism of angle A and emerges normally from the opposite face. If refractive index of the prism is μ, angle of incidence is nearly equal to:
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Question

A ray is incident at angle i on one surface of a small-angle prism of angle A and emerges normally from the opposite face. If refractive index of the prism is μ, angle of incidence is nearly equal to:

Options

G1 Physics · Accepted Answer

Step 1: Prism angle A = r₁ + r₂. Since ray emerges normally at second face, r₂ = 0. Thus r₁ = A. Step 2: At first face, sin i = μ sin r₁. Step 3: For small angles i and A, sin i ≈ i, sin A ≈ A (radians). Hence i ≈ μA. Final answer: (B) μA.