Q10.6 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 wavelength 650 nm.
Given,
The wavelength of one light beam :
The wavelength of another Light beam
Let, the distance between the two-slit be and distance between slit and screen is
NOW,
As we know, the distance of nth bright fringe from central maxima is given by
so for 3rd fringe,
Hence distance of 3rd fringe from central maxima is . Here value D and d are not given in the question.