A beam of unpolarised light of intensity is passed through a polaroid A and then through another polaroid B which is oriented so that its principal plane makes an angle of `45^(@)` relative to that of A. The intensity of the emergent light

Options

A. `(I_(0))/(8)`
B. `I_(0)`
C. `(I_(0))/(2)`
D. `(I_(0))/(4)`

Answer

D

Explanation

From Malus. law, the intensity of emergent light from polaroid A,
`I_(1)=I_(0) cos^(2) theta`
`I_(1)=(I_(0))/(2)`
The intensity of emergent light from polaroid
`I_(2)=I_(1) cos^(2) theta`
`=(I_(0))/(2)cos^(2)45^(@)`
`=(I_(0))/(2)xx(1)/(2)=(I_(0))/(4)`