Physics · Light
Refraction of Light (Snell's Law)
Light changes speed when it enters a different medium, so it bends. This is refraction.
- Angle of incidence i
- 40°
- Angle of refraction r
- 25°
- Critical angle
- None (light goes into a denser medium)
Light starts in
and enters
Try this
- Light from air into glass: does it bend towards or away from the normal?
- Light from glass into air at a large angle: what happens?
- Find the critical angle for water to air.
Key ideas
- n₁ sin i = n₂ sin r (Snell's law).
- Into a denser medium, light bends towards the normal.
- Beyond the critical angle, light reflects completely (total internal reflection).