Question

Monochromatic coherent light passing through two thin slits is viewed on a distant screen. Are the bright fringes equally spaced on the screen? If so, why? If not, which ones are

closest to being equally spaced?

Answer 1

monochromatic light is used so that we do not obtain colourful fringes and if we discuss about width of bright fringes the we ca see that fringe width will be equal to (wavelength) x (D\d) and is constant hence bright fringes are equally spaced.