A beam of light of wavelength 600 nm from a distant source falls on a single slit 1 mm wide and the resulting diffraction pattern is observed on a screen 2 m away. What is the distance between the first dark fringe on either side of the central bright fringe?

Explanation

Given data : Wavelength of light `lamda = 600 nm`
` = 600 xx 10^(-9) m`
Distance between the source & slit (screen) D = 2 m
The width of the slit d `= 1mm = 1 xx 10^(-3) m`
To find : Distance between the two dark fringes which are on either side of the central bright fringe = ?
Formula : Fringe width in single slit experiment `beta = (lamda D)/(d)`
` beta = 600 xx 10^(-9) xx (2)/((1 xx 10^(-3)) `
`beta = 1.2 mm`
Distance between dark fringes which are on either of the central bright fringe `= 2 xx 12 = 24` mm.