Malus Law : This law states that intensity of poalrised light transmitted through the analyser varies as the square of the cosine of the angle between the plane of transmission of the analyser and the plane of the polariser.
Proof: Consider the plane polarised light of intensity `I_(0)` and amplitude A is incident on the polariser.
Lt `theta` is the angle between the plane of polariser and the analyser.
On resolving A into components, we have
(i) A cos `theta` along OP along the plane of transmission of analyser
(ii) A `"sin"theta`, perpendicular to the plane of the analyser.
We know that, intensity `prop("Amplitude")^(2)`
`therefore` Intensity of transmitted light through the analyser is given by
`Iprop("A cos"theta)^(2)=kA^(2)"cos"^(2)theta`.
But `kA^(2)=I_(0)` (Intensity of incident light)
`I=I_(0)"cos"^(2)thetarArrIprop"cos"^(2)theta`. Whichb is Malus law.
