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Question
When unpolarized light is passed through a polarizer, its intensity ______.
Options
Increases
Decreases
Remain unchanged
Depends on the orientation of the polarize
Solution
When unpolarized light is passed through a polarizer, its intensity decreases.
Explanation:
According to Malu’s law,
`I = I_0 cos^2 (theta)`
Here `theta` is the angle between the axes of polarizers and `I_0` is the falling intensity.
So when unpolarized light passes through a polarizer, the intensity is reduced by a factor of `1/2`. The average `cos^2 theta`, averaged over all angles `theta` is `1/2`.
`I = I_0 <<cos^2 (theta)>>_("allangles")`
= `1/2 I_0`
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