Answer to Question #152722 in Optics for Viccy

Question

What is malus law

Answer 1

Malus law states that the intensity of plane-polarized light that passes through an analyzer varies as the square of the cosine of the angle between the plane of the polarizer and the transmission axes of the analyzer.

The law helps us quantitatively verify the nature of polarized light. Let us understand the expression for Malus’ law.

Point 1 – When Unpolarized light is incident on an ideal polarizer the intensity of the transmitted light is exactly half that of the incident unpolarized light no matter how the polarizing axis is oriented.

Point 2 – An ideal polarizing filter passes 100% of incident unpolarized light, that is polarized in the direction of filter’s (Polarizer) Polarizing axis.

From point (1) and point (2) we can assume I = I_o cos² ϕ