Light travels from vacuum ($\mu_1 = 1.0$) into glass of refractive index 1.5, striking the surface at an angle of incidence of $30^\circ$. What is the sine of the angle of refraction?

1. Snell's law: $\mu_1 \sin i = \mu_2 \sin r$. 2. Substitute: $(1.0)\sin 30^\circ = (1.5)\sin r$. 3. Since $\sin 30^\circ = 0.5$: $0.5 = 1.5 \sin r$. 4. Solve: $\sin r = \dfrac{0.5}{1.5} = 0.333$. 5. The value $0.5$ is the incident sine, not the refracted one, so it is a trap distractor. _Source: Samacheer Kalvi (TN SCERT) Class 10 Science, Unit 2 Optics "Refraction of Light", p.24_