Practice question

**Refractive index** n = c/v, water 1.33 means light 1.33 times slower than vacuum. Passing from water to air at 49°, n₁ sinθ₁ =1.33×sin49°≈1.33×0.755=1.004>1, so sinθ₂>1 impossible, total internal reflection occurs, no refraction. Snell’s law: n₁ sin i = n₂ sin r . Air ( n₁ = 1 ), glass ( n₂ = 1.5 ), i = 30° . 1 × sin 30° = 1.5 × sin r . sin 30° = 0.5 ⇒ 0.5 = 1.5 sin r ⇒ sin r = (0.5/1.5) = 0.333 . r = sin⁻¹(0.333) ≈ 19.5° . Substituting values gives 19°, which matches expected image position and magnification from