Two polaroids are kept with their polarising axes parallel; the transmitted intensity is $I$. One polaroid is then rotated through 45°. The new transmitted intensity is:
A$I/2$
B$I/4$
C$I/\sqrt 2$
D$I \cos 45°$
Answer & Solution
Correct answer: A. $I/2$
Originally $\theta = 0$, $I = I_{1}\cos^2 0 = I_1$. After 45° rotation: $I' = I_1 \cos^2 45° = I_1/2 = I/2$. Halves.
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