A beam of light of wavelength 600 nm from a distant source falls on a single slit 1.0 mm wide and the resulting diffraction pattern is observed on a screen 2 m away What is the distance between the second bright fringe on either side of the central bright fringe ?

Explanation

For the diffraction at a single slit, the position of maxima is given by
`a sin theta =(2n+1) lambda/2`
For small value of `theta, sin theta approx theta = y/D`
For second bright fringe, `n=2`
`:. Axxy/D=(5lambda)/2 or y= (5lambda)/(2a)D`
Substituting the values, we have
`y= (5xx2xx6xx10^(-7))/(2xx1xx10^(-3))=3.0xx10^(-3)m=3.0mm`
Distance between second maximum on either side of central maxima `=2y=6.0 mm`