A beam of light of wavelength 600 nm from a distance source falls on a single slit 2 mm wide and the resulting diffraction pattern is observed on a screen 2m away. What is the distance between the first dark fringes on either side of central bright fringe ?

Explanation

Given, `lambda=600nm, a=2xx10^(-3)m and D=2m`
Distance of first dark fringe from centre `y_(1)=(Dlambda)/a`
Distance between the first dark fringes on either side of the central bright fringe,
`2y_(1)=(2Dlambda)/a=(2xx2xx600xx10^(-9))/(2xx10^(-3))=1200xx10^(-6)m`
`=1.2xx10^(-3)m=1.2mm`