In a Young's double-slit experiment, the slits are separated by 0.28 mm and the screen is placed 1.4m away. The distance between the central bright fringe and the fourth bright fringe is measured to be 1.2 cm . Determine the wavelength of light used in the experiment.

Explanation

Given, slit separation , `d = 0.28 mm = 0.28 xx 10^(-3) m` distance between the screen and slits is, `D = 1.4 m` Distance between central bright fringe and the fourth bright fringe, `y = 1.2 xx 10^(-2) m`
`n = 4`
Since, `y = D/d n lambda`
`implies lambda = y/n d/D`
`lambda = (1.2 xx 10^(-2) xx 0.28 xx10^(-3))/(4 xx 1.4) m`
`lambda = 600 xx 10^(-9) m = 600 nm`.