As shown in the figure,three identical polaro | vedclass

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(A) Let the initial intensity of the unpolarized light from source $S$ be $I_0 = 256 	ext{ W/m}^2$.When unpolarized light passes through the first po

Vedclass · Accepted Answer

$24$

Vedclass · Answer

(A) Let the initial intensity of the unpolarized light from source $S$ be $I_0 = 256 	ext{ W/m}^2$.When unpolarized light passes through the first polaroid $P_1$,the intensity becomes $I_1 = \frac{I_0}{2} = \frac{256}{2} = 128 	ext{ W/m}^2$.According to Malus' Law,when polarized light passes through a second polaroid with its pass axis at an angle $	heta$ to the polarization direction of the incident light,the transmitted intensity is $I = I_{incident} \cos^2(	heta)$.For $P_2$,the angle with $P_1$ is $	heta_1 = 60^{\circ}$. So,$I_2 = I_1 \cos^2(60^{\circ}) = 128 	imes (\frac{1}{2})^2 = 128 	imes \frac{1}{4} = 32 	ext{ W/m}^2$.For $P_3$,the angle with $P_2$ is $	heta_2 = 90^{\circ} - 60^{\circ} = 30^{\circ}$. So,$I_3 = I_2 \cos^2(30^{\circ}) = 32 	imes (\frac{\sqrt{3}}{2})^2 = 32 	imes \frac{3}{4} = 24 	ext{ W/m}^2$.Thus,the intensity at point $O$ is $24 	ext{ W/m}^2$.

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