Two-Source
Interference
๐ต Sโ โ Blue source
๐ด Sโ โ Red source
โโ Crest (wave peak)
- - - Trough (wave valley)
Each source shows 7 crests and 7 troughs, spaced one wavelength (ฮป) apart.
๐ Click on the diagram
Click anywhere on the wavefront pattern to place an observation point (โ).
The path lengths from Sโ and Sโ will be calculated and the interference type will be determined.
๐ก Interference condition
โข Constructive: |dโ โ dโ| = nฮป
โข Destructive: |dโ โ dโ| = (n+ยฝ)ฮป
The lower diagram shows sinusoidal waves from Sโ and Sโ meeting at P. Both waves start at a crest.