What is Diffraction?
Diffraction is the phenomenon where waves bend as they pass around obstacles or through small openings. This bending effect causes the waves to spread out from their original direction of propagation, allowing them to reach areas that would otherwise be shielded by the obstacle.
How Diffraction Works
When a wavefront encounters an edge, a slit, or a small aperture, the points on the wavefront act as new sources of secondary waves, according to Huygens' principle. These secondary waves interfere with each other, leading to a spreading pattern rather than a sharp shadow. The extent of diffraction depends on the wavelength of the wave and the size of the obstacle or opening.
Examples of Diffraction
A common example is seeing a faint, blurry edge or fringes around shadows, especially when the light source is small. The rainbow-like patterns observed on the surface of a CD or DVD are also due to the diffraction of light by the tiny grooves. Similarly, you can hear sound from around a corner, even if you can't see the source, because sound waves diffract around the obstacle.
Importance and Applications
Diffraction is a fundamental wave property crucial in many scientific fields. It sets the resolution limits for optical instruments like microscopes and telescopes. It's also utilized in technologies such as X-ray crystallography to determine the atomic and molecular structure of crystals, in holography to create 3D images, and in optical gratings for spectroscopic analysis.