Young’s Double Slit Experiment

In 1803 Thomas Young settled a debate started over 100 years earlier between Newton and Huygens by demonstrating the interference of light. Newton thought that light was made up of tiny particles called corpuscles and Huygens thought that light was a wave, Young’s interference of light proves light is a wave. Here is Young’s double slit set up, the two slits act as coherent sources of waves

Interference occurs where the light from the two slits overlaps. Constructive interference produces bright areas, while deconstructive interference produces dark areas. These areas are called interference fringes.

Fringes

There is a central bright fringe directly behind the midpoint between the slits with more fringes evenly spaced and parallel to the slits.

As we move away from the centre of the screen we see the intensity of the bright fringes decreases.