A beam of light consisting of red, green and blue colours is incident on a right-angled prism. The refractive index of the material of the prism for red, green and blue wavelengths is 1.39, 1.44 and 1.47 respectively. The prism will:
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Question

A beam of light consisting of red, green and blue colours is incident on a right-angled prism. The refractive index of the material of the prism for red, green and blue wavelengths is 1.39, 1.44 and 1.47 respectively. The prism will:

Options

G1 Physics · Accepted Answer

Step 1: Critical angle C = sin⁻¹(1/μ); larger μ means smaller C. Step 2: At internal incidence 45°, compare μ with √2 ≈ 1.414. Step 3: Red (μ = 1.39) has C > 45°, so it refracts out. Green and blue (μ = 1.44 and 1.47) have C < 45°, so they totally internally reflect. Final answer: (D) red separated from green and blue.