How to Calculate Distance Between Fringes in Double Slit Experiment

Explanation:

As per Young's double slit experiment, the distance between the fringes can be observed for the bright constructive interference fringes. So if we know the distance between the separation of slits, the distance of the mirror placed away from the slit, then the distance between two fringes can be observed using the below formula.

y = (m * wavelength * D) / d

Here, y is the distance between the fringes on the screen, D is the distance of the screen from the slits, and d is the distance between the slits. Also, m is the order of the interference which is generally considered as 1.

So, in the given case, D = 30.8 cm = 0.308 m, d = 6.53×10⁻³ m, wavelength = 478 nm, and m = 1.

Therefore, y = (1 * 478 * 10⁻⁹ * 0.308) / 6.53 * 10⁻³

y = 22.546 * 10⁻⁹+3 = 22.546 * 10⁻⁶ m = 0.0225 mm

So, the distance between the two fringes is 0.0225 mm.