In Young's double slit experiment, the distnace between two sources is `0.1//pimm`. The distance of the screen from the source is 25 cm. Wavelength of light used is `5000Å` Then what is the angular position of the first dark fringe.?

Explanation

The angular position `theta=(beta)/(D)=(lamda)/(d)(thereforebeta=(lamdaD)/(d))`
the first dark fringe will be at half the fringe width from the mid point of central maximum. Thus the angular position of first dark fringe will be-
`alpha=(theta)/(2)=(1)/(2)[(lamda)/(d)]=(1)/(2)[(5000xxpi)/(1xx10^(-3))xx10^(10)](180)/(pi)=0.45^(@)`