Malus' law

American  

[muh-loos law, ma-lys] / məˈlus ˈlɔ, maˈlüs /

noun

Optics.

1. the law stating that the intensity of a beam of plane-polarized light after passing through a rotatable polarizer varies as the square of the cosine of the angle through which the polarizer is rotated from the position that gives maximum intensity.

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Etymology

Origin of Malus' law

Named after E. L. Malus (1775–1812), French physicist