Two slits at a distance of `1mm` are illuminated by a light of wavelength `6.5xx10^-7m`. The interference fringes are observed on a screen placed at a distance of `1m`. The distance between third dark fringe and fifth bright fringe will be

Options

A. `0.65mm`
B. `1.63mm`
C. `3.25mm`
D. `4.88m`

Answer

B

Explanation

Distance between `n^(th)` bright fringe and `m^(th)` dark fringe `(ngtm)`
`Deltax=(n-m+1/2)beta=(5-3+1/2)xx(6.5xx10^-7xx1)/(1xx10^-3)`
`=1.63mm`