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(B) When unpolarised light of intensity $I_0$ passes through the first polaroid,the intensity of the transmitted light is $I_1 = I_0 / 2$.For subseque

Vedclass · Accepted Answer

$\frac{27 I_0}{128}$

Vedclass · Answer

(B) When unpolarised light of intensity $I_0$ passes through the first polaroid,the intensity of the transmitted light is $I_1 = I_0 / 2$.For subsequent polaroids,we use Malus' Law: $I_n = I_{n-1} \cos^2 	heta$,where $	heta = 30^{\circ}$.Intensity after the second polaroid: $I_2 = I_1 \cos^2 30^{\circ} = (I_0 / 2) 	imes (\sqrt{3} / 2)^2 = (I_0 / 2) 	imes (3 / 4) = 3 I_0 / 8$.Intensity after the third polaroid: $I_3 = I_2 \cos^2 30^{\circ} = (3 I_0 / 8) 	imes (3 / 4) = 9 I_0 / 32$.Intensity after the fourth polaroid: $I_4 = I_3 \cos^2 30^{\circ} = (9 I_0 / 32) 	imes (3 / 4) = 27 I_0 / 128$.Thus,the correct option is $B$.

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