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Two polarising sheets are placed with th...

Two polarising sheets are placed with their planes parallel, so that light intensity transmitted is max. Through what angle must either sheet be turned so that light intensity drops to half the maximum value ?

Text Solution

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According to law of Malus, `I = I_(0) cos^(2)theta`
`:. Cos^(2) theta = (I)/(I_(0)) = (1)/(2), cos theta = +- (1)/(sqrt(2))`
`:. theta = +- 45^(@) or +- 135^(@)`
The effect will be same, when any of the sheets is turned through `theta` in any direction.
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