Unpolarized light with intensity 300 W m2 is incident on three polarizers, P1, P2, and P3 numbered in the order light reaches the polarizers. The transmission axis of P1 and P2 make an angle of 45?. The transmission axis of P2 and P3 make an angle of 30?. How much light is transmitted through P3? Select One of the Following: (a) 60 W m2 (b) 100 W m2 (c) 20 W m2 (d) 10 W

answer is A corresponding to 60 W

Explanation:

The polarization phenomenon is descriptor Malus's law

I = I₀ cos² θ

Where I and Io are the transmitted and incident intensities, respectively, θ is the angle between the direction of polarization of the light and the polarizer.

Unpolarized light strikes the first polarizer and half of it is transmitted, which has the polarization direction of the polarizer

I₁ = ½ I₀

I₁ = ½ 300

I₁ = 150 W

The transmission by the second polarizer (P2) is

I₂ = I₁ cos² θ 1

I₂ = 150 cos² 45

I₂ = 75 W

The transmission of the third polarizer (P3)

I₃ = I₂ cos² θ 2

I₃ = 75 cos² 30

I₃ = 56.25 W

This is the light transmitted by the 56 W system, the closest answer is A corresponding to 60 W