Lesson: Chapter 5 — Optics

5.3. Refraction of light 5 of 5

Denser and rarer media

Activity 5.4 gives a rule that works for any two media.

Rarer → denser

The ray bends towards the normal: r is smaller than i.

Denser → rarer

The ray bends away from the normal: r is larger than i.

Light going from water up into air, bending away from the normal: the angle of refraction r is larger than the angle of incidence i.

Turn it round: if a ray bends towards the normal on entering a medium, that medium is denser than the first; if it bends away, it is rarer.