Page 14 - Topic 3

FRINGE SEPERATION

The distance between adjacent bright fringes (or dark fringes) is constant.
The distance is called the fringe separation Δ .

Δ =

Where:

is the fringe width (m)

is the wavelength (m)

L is the distance between the slits and the screen\

D is the distance between the slits.

EXAMPLES

A Young’s double slit interferometer is illuminated with green light of wavelength 546nm. The double slits are
0.100mm apart and the screen is 20.0cm away from the double slits. Find:

1. The angular position of the first minimum on the screen;
2. The angular position of the fifth maximum on the screen;
3. The distance, on the screen, between the first maximum and the fifth maximum.