Two polaroids are placed in the path of unpolarized beam of intensity I 0 such that the intensity of light emitted from the second polaroid is `9/50 l_(0).` If third polaroid whosepolarization axis makes an angle `theta` with the polarization axis of first polaroid, is placed between these polaroids, such that the intensity of light emerging from the last polaroid is zero, then angle `theta `is

Options

A. `37^(@)`
B. `53^(@)`
C. `60^(@)`
D. `30^(@)`

Answer

A

Explanation

Let initial intensity of light is `I_(0).` So intensity of light after ternsmission from first polariod `= (I_(0))/(2).`
Let `phi` be angle between `1 ^(st) and 2 ^(nd)` polaroid
Hence, `(9)/(50) I_(0) =(I_(0))/(2) cos ^(2) phi`
`cos phi = (9)/(25) ( phi = 53^(@))` ltbr From gigure `phi + theta = 90^(@)`

`therefore theta = 37^(@)`