In a double slit experiment, the distance between the slits is d. The screen is at a distance D from the slits. If a bright fringe is formed opposite to one of the slits, its order is

Options

A. `(d)/(lambda)`
B. `(lambda^(2))/(dD)`
C. `(D^(2))/(2lambda D)`
D. `(d^(2))/(2D lambda)`

Answer

D

Explanation

When a bright frings is formed opposite to one of the slits, `x=(d)/(2)`
Path difference `=(xd)/(D)=(d)/(2)xx(d)/(D)=(d^(2))/(2D)`
If it is `n^(th)` order bright fringe,
Path difference, `n lambda=(d^(2))/(2D) " or "n=(d^(2))/(2D lambda)`