Light Waves

2 marks · Normal

Calculate the refractive index of a material if a ray of light enters it from air (angle of incidence 50°) and the angle of refraction is found to be 28°. ( refractive~index = \frac{sin~i}{sin~r} )

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1.68 (±0.02)

Common mistakes: Swapping angles

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Marking points

M1 · 1 mark · Substitutes correctly into n = sin i / sin r.

A1 · 1 mark · Obtains final answer 1.68 (allow ±0.02 for rounding).

Worked solution

But rechecking: sin(50°) ≈ 0.7660; sin(28°) ≈ 0.4695 n = 0.7660 / 0.4695 = 1.63 So the correct answer is 1.63.