In young's double slit experiment the distance between two sources is`0.1//pimm`.the distance of the screen from the source is `25cm`.wavelength of light used is `5000Å`.Then the angular position of the first dark fringe is-

Options

A. `0.9^(@)`
B. `0.15^(@)`
C. `0.3^(@)`
D. `0.45^(@)`

Answer

D

Explanation

`d=(0.1)/(pi)mm,lamda=500mm,x_(1)d=?`
`x_(1)d=0.5theta`
`=0.5(lamda)/(d)`
`=(0.5xx5xx10^(-7))/((0.1)/(pi)xx10^(-3))` rad
`=2.5xxpixx10^(-3)rad`
`(2.5xxpixx10^(-3)xx180)/(pi)` deg
=0.45 deg