In Young’s double-slit experiment, the interference pattern forms because light waves coming from the two slits overlap and combine on the screen. Here’s how it happens:
- Coherent light sources:
The two slits act as coherent sources of light waves that have a constant phase relationship. - Wave overlap:
As the waves spread out from each slit, they overlap with each other at various points on the screen. - Path difference:
The difference in distance traveled by the waves from each slit to a point on the screen determines how they combine. - Constructive interference:
When the path difference is a whole number multiple of the wavelength, the waves arrive in phase, reinforcing each other and creating a bright fringe (maximum intensity). - Destructive interference:
When the path difference is a half-integer multiple of the wavelength, the waves arrive out of phase, canceling each other out and producing a dark fringe (minimum intensity). - Pattern formation:
The alternating bright and dark fringes appear as a series of parallel bands on the screen, called the interference pattern.
This pattern visually demonstrates the wave nature of light through the principle of superposition and interference.