In a Young's double slit experiment, the separation between the two slits is 0.9 mm and the fringes are observed one metre away. If it produces the second dark fringe at a distance of 1 mm from the central fringe, the wavelength of the monochromatic source of light used is

Step-by-step solution

The distance between two consecutive dark or bright fringes is recognised as (fringe width) and that between central fringe and first dark fringe on either side is 2 . Given, spacing between second dark fringe and central fringe = + 2 or 3 2 =1 ~mm (Given) or = 2 3 1 ~mm or D d = 2 3 ~mm array ll & = 2 3 10⁻³ 0.9 10⁻³ 1 & =0.6 10⁻⁶ ~m array Wavelength of the monochromatic source of light =600 10⁻⁹ ~m =600 ~nm