A pair of identical narrow slits is illuminated simultaneously by two monochromatic radiations of wavelengths 650nm (red) and 520nm (green). The slit separation is 0.40mm and the screen is kept 1.8m away.
(a) Show that certain bright fringes of the two colours coincide on the screen. Obtain the least order m (counted from the central maximum) at which such a coincidence occurs.
(b) Calculate the linear distance of this coincident bright fringe from the central maximum.
(c) How many bright fringes of the green light lie within the distance found in part (b)?