WAEC Physics 2019 Paper

Concept:When light moves from a denser medium (glass) to a rarer medium (air), it bends away from the normal, so the angle of refraction is larger than the angle of incidence.Explanation:Given: refractive index of glass, $n_g = 1.5$; refractive index of air, $n_a = 1$.Angle of incidence inside the glass, $i = 30^\circ$.Let the angle of refraction in air be $r$.Using Snell's law:$$n_g \sin i = n_a \sin r$$Substitute the values:$$1.5 \times \sin 30^\circ = 1 \times \sin r$$Since $\sin 30^\circ = 0.5$:$$\sin r = 1.5 \times 0.5 = 0.75$$Therefore:$$r = \sin^{-1}(0.75) = 48.6^\circ$$This matches the correct choice among the options.Answer:The angle of refraction is $48.6^\circ$.