How to find sin i and sin r?

To find sin i (sine of angle of incidence) and sin r (sine of angle of refraction):

1. Measure the angles using a protractor or calculation from experimental data
2. Use a calculator or trigonometric tables to find the sine values
3. Alternatively, if you know the refractive indices, use Snell's law: n₁ sin i = n₂ sin r

For example, if light travels from air (n=1) to water (n=1.33) at 30° incidence:

• sin i = sin 30° = 0.5
• sin r = (n₁ sin i)/n₂ = (1 × 0.5)/1.33 ≈ 0.376, so r ≈ 22°