Young's Double-Slit Experiment: Interference Patterns

Interference pattern with increased wavelength

The fringes spread farther apart

Effect of decreased slit separation (d)

Fringe spacing increases

Use of monochromatic light source in Young's experiment

It ensures a clear and stable interference pattern

Condition for constructive interference

Path difference between waves is a multiple of the wavelength (0, λ, 2λ, ...)

Reason for dimming bright fringes

One of the slits is partially blocked

Effect of increasing distance (L) between slits and screen

The fringes spread farther apart

Meaning of a 'missing order'

A bright fringe that is missing because of overlap with a dark fringe from diffraction

Pattern observed with white light

A series of colored fringes, like a rainbow pattern

Assumption of screen being far from slits

To simplify the mathematical analysis and get clear fringes

Advantage of using a lens at the focal point

It brings the far-field pattern closer for easier observation