Light diffraction is a fundamental wave phenomenon that occurs when light encounters obstacles or passes through openings. When light waves meet a barrier with an opening comparable to their wavelength, they bend and spread out, creating characteristic interference patterns. This demonstrates that light behaves as a wave, not just as particles.
Single slit diffraction occurs when light passes through an opening whose width is comparable to the wavelength of light. The resulting pattern shows a bright central maximum with alternating dark and bright fringes on either side. The width of the slit determines the spread of the diffraction pattern - narrower slits produce wider patterns.
Double slit diffraction demonstrates wave interference when light passes through two parallel slits. The waves from each slit interfere with each other, creating a pattern of alternating bright and dark fringes. Bright fringes occur where waves constructively interfere, while dark fringes result from destructive interference. The spacing between fringes depends on the slit separation.
A diffraction grating contains many parallel slits that work together to produce sharp, well-defined spectral lines. Unlike single or double slits, gratings create multiple orders of diffraction with high resolution. The more slits in the grating, the sharper and brighter the spectral lines become. This makes gratings essential tools in spectroscopy for analyzing the composition of light sources.