A ray of light passes from air into a glass slab of refractive index 1.5. If the angle of incidence is 30°, what is the angle of refraction?
Correct: B
Using Snell's law, n1 sin(θ1) = n2 sin(θ2), where n1 is the refractive index of air, θ1 is the angle of incidence, n2 is the refractive index of glass, and θ2 is the angle of refraction. Substituting the given values, we get (1) * sin(30°) = (1.5) * sin(θ2), which gives sin(θ2) = (1/1.5) * sin(30°) = (1/1.5) * 0.5 = 0.333, so θ2 = arcsin(0.333) = 19.5°, which is closest to 20°.