Q. Three polaroid sheets $P_1, P_2$ and $P_3$ are kept parallel to each other such that the angle between pass axes of $P_1$ and $P_2$ is $45^\circ$ and that between $P_2$ and $P_3$ is $45^\circ$. If unpolarised beam of light of intensity $128 Wm^{-2}$ is incident on $P_1$. What is the intensity of light coming out of $P_3$?
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