Malus's Law Virtual Experiment

Optical bench

Red 650 nm diode laser, linearly polarised (Class 2, at most 1 mW). It sits in a rotation mount; turning it sets the source polarisation angle.

Source polarisation angle

Source intensity

Intensity only scales the light's power; the polarisation and the fraction each polariser passes stay the same.

1 of 3

P11 of 1 along the beam

Transmission axis angle

Position on rail

Show the electric-field wave

Each polariser passes cos²θ of what reaches it; θ is the angle between that light's polarisation and its transmission axis.

Complete each step; the missions track your progress.

The curve is the intensity on the screen as P1 turns, all else fixed; the red dot is the current setting.

Looking along the beam; the arrow length is the field amplitude (√I) and the percentage the intensity relative to the laser.

25.0%

I = 0.250 I₀

Output polarisation

60°

One polariser in the beam; the transmitted intensity follows Malus's law.