An Etymological Dictionary of Astronomy and Astrophysics

If the light wave entering an → analyzer is → linearly polarized, the intensity of the wave emerging from the analyzer is I = k I₀ cos²φ,

where k is the coefficient of transmission of the analyzer, I₀ is the intensity of the incident light, and φ is the angle between the planes of → polarization of the incident light and the light emerging from the analyzer.

See also: Named after Etienne Louis Malus (1775-1812), French physicist who also discovered polarization by reflection at a glass surface (1808); → law.