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Question
Unpolarised light is incident on a polaroid. How would the intensity of transmitted light change when the polaroid is rotated?
Solution
If the unpolarised light is incident on a Polaroid the intensity is reduced by half. Even if the Polaroid is rotated by angle θ the average over cos2θ = ½. Thus from Malus’ law: I = I0cos2θ
Or, = < I0cos2θ > = I0< cos2θ > = I0/2
Thus, the intensity of the transmitted light remains unchanged when the Polaroid is rotated.
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