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Question
Two polaroids P1 and P2 are placed with their pass axes perpendicular to each other. An unpolarised light of intensity Io is incident on P1. A third polaroid P3 is kept in between P1 and P2 such that its pass axis makes an angle of 45° with that of P1. Determine the intensity of light transmitted through P1, P2 and P3
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Solution
As given in the question, the polaroids P1 and P2 are placed with their pass axes perpendicular to each other. Also, P3 is placed at an angle of 45° with respect to P1.
Now, we have:
Intensity of light after falling on P1 `I'=I_0/2`
Intensity of light after falling on P3 I"=
`I'cos^2(theta)=I_0/2cos^2(45^@)=I_0/4`
Therefore, a light of intensity `I_0/4`will pass through P3 and the angle between P3 and P2 will be 45° because of the condition given in the question.
Intensity of light after falling on P2 I''' = I'' `cos^2(theta)=I_0/4cos^2(45^@)=I_0/8`
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