A light ray travels from water (n = 1.33) into a transparent solid. The angle of incidence in water is 50°, and the angle of refraction in the solid is 30°. What is the refractive index of the solid? (Use sin 50° = 0.766 and sin 30° = 0.500)
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Correct answer
A. 2.04
Principle or equation
Snell's law: n1 sin θ1 = n2 sin θ2.
Why this answer is correct
Given n1 = 1.33, θ1 = 50°, θ2 = 30°. Solve for n2: n2 = n1 sin θ1 / sin θ2 = (1.33 × 0.766) / 0.500 = 1.01878 / 0.500 = 2.0376 ≈ 2.04.
Example
If light goes from air (n=1) into glass at incidence 30° and refraction 19.5°, n_glass = sin30/sin19.5 = 0.5/0.333 = 1.50.
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