In this experiment, Malus' Law of Polarization is verified by showing that the intensity of light passed through 2 polarizers depends on the square of the cosine of the angle between the 2 polarization axes.

Laser light (peak wavelength = 650 nm) is passed through 2 polarizers. As the second polarizer (the analyzer) is rotated by hand, the relative light intensity is recorded as a function of the angle between the axes of polarization of the 2 polarizers. The angle is obtained using a Rotary Motion Sensor coupled to the polarizer with a drive belt. The plot of light intensity versus angle can be fitted to the square of the cosine of the angle.

PASCO Advantage:
Laser light is used in this experiment because its wavelength is more completely extinguished by the crossed polarizers.