A beam of light consisting of two wavelengths `650 nm` and `520 nm` is used to obtain
Channel: Doubtnut
Date: 16/08/2020

A beam of light consisting of two wavelengths `650 nm` and `520 nm` is used to obtain interference fringes in a Young's double slit experiment.   (a) Find the distance of the third bright fringe on the screen from the central maximum for the wavelength `650 nm`.   (b) What is the least distance from the central maximum where the bright fringes due to both the wavelengths coincide? The distance between the slits is `2 mm` and the distance between the plane of the slits and screen is `120 cm`.