In a two slit experiment with monochromatic light, fringes are obtained on a screen placed at some distance from the slits . If the screen is moved by `5xx10^-2m`, towards the slits, the change in fringe width is `3 xx 10^-5`m. If separation between the slits is `10^-3`m, the wavelength of light used is

Explanation

`beta=(Dlambda)/d …(i)`
When D decreases, fringe width decreases
`beta-30xx10^(-6)=((D-5xx10^(-2))lambda)/d …(ii)`
(i)-(ii)
`30xx10^(-6)=(5xx10^(-2)lambda)/d=(5xx10^(-2)lambda)/(1xx10^(-3))`
`lambda=(30xx10^(-6)xx10^(-3))/(5xx10^(-2))`
`=6xx10^(-7) m`
`=600xx10^(-9) m`
`=600 nm`