Key Concepts: Polarization

What is Polarization?

• Polarization restricts the oscillation direction of a transverse wave to a single plane.
• Only transverse waves can be polarized — this confirms light is a transverse wave.
• Unpolarized light oscillates in all directions perpendicular to propagation.

Methods of Polarization

• Polarizing filters: Absorb one component — only aligned vibrations pass (e.g., Polaroid sunglasses).
• Reflection: Reflected light is partially polarized. At Brewster's angle, reflected light is fully polarized.
• Scattering: Scattered light (blue sky) is partially polarized.

Malus's Law

• When polarized light passes through a second polarizer (analyzer) at angle θ:
• I = I₀ cos² θ.
• At θ = 0°: full transmission. At θ = 90°: zero transmission (crossed polarizers).