Snell's law: angle of refraction
Light in air strikes glass (n = 1.5) at 30° from the normal. What is the angle of refraction?
Answer A: explanation for every choice
A
Correct. sin r = (1.0)(sin 30°)/1.5 = 0.5/1.5 = 0.333, so r ≈ 19.5°. Light bends toward the normal.
B
This assumes no bending, which happens only when the indices are equal.
C
This multiplies the angle by the index, which isn't how Snell's law works.
D
This puts n on the wrong side: sin r = 1.5 × 0.5 = 0.75.
Takeawayn₁ sin θ₁ = n₂ sin θ₂. Into a higher n → bends toward the normal.
Equation usedIndex of refraction and Snell's law
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