According to this law, “when a beam of completely plane polarised light is incident on an analyser, the resultant intensity of light I transmitted from the analyser varies directly as the square of the cosine of the angle between the plane of transmission of analyser and polariser”.
I = I0 cos2 θ [this rule is also called cosine squared rule] Where, I0 is the intensity of the polarised light after passing through P.
