Wave Polarisation

Malus's law: I = I_max cos²θ. Drag a filter, or use the sliders.

Source intensity (I₀)100.0 W/m²

After the polariser (I₁)50.0 W/m²

After the analyser (I₂)50.0 W/m²

Angle between the filters (Δθ)0.0°

Swipe the picture sideways to see the whole wave.

1. Unpolarised source
The electric field points in all directions.

2. After the polariser
Only one direction is left, with half the intensity.

3. After the analyser
The part along the analyser's axis gets through.

Polariser angle (θ₁) 0°

Analyser angle (θ₂) 0°

Wave frequency, slowed down (f) 1.2 Hz Show the filter grids Include the analyser

What are the grids, and is this the real frequency?

The grids stand for the long polymer chains in a polarising filter. They absorb the part of the electric field that is parallel to the chains, so the light that gets through is polarised at right angles to them.

Real light oscillates about 5 × 10¹⁴ times each second. The animation is slowed down enormously so that you can see the wave.

Learn more in the Polarisation lesson.