Question

Unpolarized light of intensity I pass through two Polaroid sheets. The axis of the first is vertical, and that of the second is at  30° , to the vertical, what fraction of the incident light is transmitted?

(a)  3/4 I

(b)  1/2 I

(c)  1/4 I

(d)  3/8 I

Answer 1

Correct option  (d)  3/8 I

Explanation:

The average value of the cosine squard function is one-half, so the first polarizer transmits 1/2 I  of the light.

The second transmits cos²(30°) = 3/4

∴ I_f  = 1/2 x 3/4 I = 3/8 I