As shown in figures, three identical polaroids P 1 , P 2 and P 3 are placed one after another. The pass axis of P 2 and P 3 are inclined at angle of 60 º and 90 º with respect to axis of P 1 . The sou

Question

As shown in figures, three identical polaroids $P_{1}$ , $P_{2}$ and $P_{3}$ are placed one after another. The pass axis of $P_{2}$ and $P_{3}$ are inclined at angle of $60 º$ and $90 º$ with respect to axis of $P_{1}$ . The source $S$ has an intensity of $256 W m^{- 2}$ . The intensity of light at point $O$ is _____ $W m^{- 2}$ .

TestHub · Accepted Answer

As given here, the pass axis of P 2 and P 3 are inclined at angle of 60 º and 90 º with respect to axis of P 1 . Therefore, intensity of light after falling on first polaroid P 1 , I 1 = I 0 2 Intensity of light after falling on second polaroid P 2 , I 2 = I 1 cos 2 60 ° = I 0 8 Intensity of light after falling on third polaroid P 3 , I 3 = I 2 cos 2 30 ° = I 0 8 3 4 = 3 I 0 32 The intensity of light at O is 3 I 0 32 = 3 × 256 32 = 24 W m - 2

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