Polarisation

The direction of the wiggle

An interactive lesson with 6 steps, about 5 minutes: you predict, drag and solve, with instant feedback on every answer. It runs in your browser and needs JavaScript.

What you’ll learn

• Polarising filters pass only light wiggling along their axis; unpolarised light loses half.
• Malus's law: transmitted fraction $\cos^2\theta$.
• Reflections are polarised, completely at Brewster's angle $\tan\theta_B = n$.

Steps

1. Which way does light wave?
2. The first filter
3. Malus’s law
4. Cutting glare
5. Brewster’s angle
6. Three filters