Calculate the distance between the centers of `4^(th) and 7^(th)` bright fringes in an interference pattern produced in young's slit experiment. Give separation between the slits `=1.1xx10^(-3)`, wavelength of light used `=589.3 nm`, and distance of the screen from the double slit `=1.3m`.

Explanation

Given `d=1.1x10^(-3) m , lambda=589.3xx10^(-9) m , D=1.3m`
We know that distance of the `n^(th)` bright fringe from the central fringe `=x=(n lambda D)/(d)`.
Hence distance between `7^(th)` and `4^(th)` bright fringes will be
`Delta x=x_7=x_4=(lambda D)/(d)(7-4)`
`=(3xx589.3xx10^(-9)xx1.3m)/(1.1xx10^(-3))`
`Delta x=2.089xx10^(-3) m `