(i) State law of Malus.

(ii) Draw a graph showing the variation of intensity (I) of polarised light transmitted by an analyser with an angle (θ) between polariser and analyser.

(iii) What is the value of the refractive index of a medium of polarising angle 60°?

(i) According to malus, when completely plane polarized light is incident on the analyzer, the intensity I of the light transmitted by the analyzer is directly proportional to the square of the cosine of the angle between the transmission axes of the analyzer and the polarizer. This is known as the Malus law.

i.e. I₀ α cos² θ or

⇒ I = I₀ cos² θ

where,

I₀ is the intensity of the light incident on the analyzer and

θ is the angle between the analyzer and the polarizer.

This can be more accurately described as,

(ii) the variation of intensity (I) of polarised light transmitted by an analyser with an angle (θ) between polariser and analyser is given as:

(iii) The relation between the refractive index of the medium and the polarizing angle can be written as:

μ = tan ϕ

where,

μ is the refractive index

ϕ is the polarizing angle

Given,

Polarizing angle, ϕ = 60°

⇒ μ = tan 60°

⇒ μ = (3)^1/2 = 1.732

The value of refractive index of a medium is 1.732