A single slit of width 0 . 1 mm is illuminated by a parallel beam of light of wavelength 6000 Å and diffraction bands are observed on a screen 0 . 5 m from the slit. The distance of the third dark band from the central bright band is:

Step-by-step solution

a = 0.1   mm = 10 - 4   m λ = 6000 × 10 - 10 = 6 × 10 - 7   m D = 0.5   m For 3 r d   dark a sin ⁡ θ = 3 λ sin ⁡ θ = 3 λ a = x D x = 3 λ D a = 3 × 6 × 10 - 7 × 0.5 10 - 4 = 9   mm