Two polaroid sheets are placed one over the other with their axes inclied to each other at an angle `theta` . If only `12.5%` of the intensity of the light incident on the first sheet emerges out from the second sheet, the value of `theta` is

Options

A. `30^(@)`
B. `60^(@)`
C. `45^(@)`
D. `90^(@)`

Answer

B

Explanation

`I = (I_(0))/(2) cos^(2) theta`
`(I)/(I_(0)) = (1)/(2) cos^(2) theta :. 12.5% = (1)/(2) cos^(2) theta`
`cos^(2) theta = 0.25 = (1)/(4) :. cos theta = 0.25 = (1)/(2)`
`:. theta = 60^(@)`