Diffraction of light is the bending and spreading of light waves when they encounter an obstacle or pass through a narrow opening (such as a slit or edge). Instead of continuing in straight lines, the waves spread out and interfere with each other, forming patterns of light and dark regions.
This behavior occurs more noticeably when the size of the obstacle or opening is comparable to the wavelength of light. The most common example is the formation of a diffraction pattern — such as a central bright fringe with alternating dark and bright fringes on either side when light passes through a single slit.
Diffraction demonstrates the wave nature of light. It is responsible for many natural and practical phenomena, including:
- The colorful patterns seen on CDs and DVDs
- The fuzzy edges of shadows
- The working of diffraction gratings used in spectrometers
- Resolving fine details in microscopes and telescopes
The amount of diffraction increases as the slit gets narrower or as the wavelength of light becomes longer.