A narrow slit of width 1 mm is illuminated by monochromatic light of wavelength 600 nm. The distance between the first minima on either side of a screen at a distance of 2 m is

For first dark fringe on either side,     dsinθ=λ  ⇒dyD=λ        [sinθ ≃ tan θ] ∴y=λDd  Therefore, distance between two dark fringes on either side = 2y=2λDd Substituting the values, we have distance = 2600×10−6mm2×103mm1.0mm=2.4 mm