Question

A beam of unpolarised light of intensity `I_0` is passed through a polaroidA and then through another polaroid B which is oriented so that its principal plane makes an angle of `45^circ` relative to that of A. The intensity of the emergent light is
A. `I_(0)`
B. `I_(0)//2`
C. `I_(0)//4`
D. `I_(0)//8`

Answer 1

Correct Answer - C
Here, polaroid `A` polarises light.
Intensity of polarised light from `A = (I_(0))/(2)`
According to law of Malus,
Intensity of light emerging from `B`,
`I_(B) = ((I_(0))/(2)) (cos 45^(@))^(2) = (I_(0))/(2)((1)/(sqrt(2)))^(2) = (I_(0))/(4)`