Diffraction explains the bending of light around obstacles by describing how light waves spread out when they encounter an edge or pass through a small opening. Instead of continuing in a perfectly straight line, the waves “bend” or spread into the region behind the obstacle or aperture.
When light encounters a barrier with a sharp edge or a slit:
- The edge acts like a new source of wavelets, according to Huygens’ principle.
- These secondary waves interfere and spread into the shadowed region.
- As a result, light is seen even in areas that are not directly in the path of the original beam.
This behavior is more noticeable when the obstacle or opening is comparable in size to the wavelength of light. That’s why small slits and edges cause visible diffraction, leading to patterns of light and dark regions due to interference of the diffracted waves.