Why do waves bend around corners?

Waves bend around corners due to a phenomenon known as diffraction.

Diffraction is a fundamental characteristic of waves, including sound, light, and water waves. It refers to the bending of waves around obstacles or the spreading of waves after they pass through a gap. This phenomenon is more noticeable when the size of the obstacle or the gap is comparable to the wavelength of the wave.

The principle of diffraction can be explained using Huygens' principle, which states that every point on a wavefront can be considered as a source of secondary wavelets. These secondary wavelets spread out in all directions with the same speed as the original wave. When the wave encounters an obstacle or a gap, the secondary wavelets on the edge will continue to spread out, causing the wave to bend around the corner.

The amount of bending, or diffraction, depends on the wavelength of the wave and the size of the obstacle or gap. If the wavelength is much smaller than the obstacle or gap, the wave will not bend much and will continue in a straight line. However, if the wavelength is comparable to or larger than the obstacle or gap, the wave will bend significantly. This is why low-frequency (long-wavelength) sound waves can be heard around corners, but high-frequency (short-wavelength) light waves cannot.

In the context of light waves, diffraction is responsible for the formation of patterns of light and dark bands, known as interference patterns, when light passes through a narrow slit or around a small object. This phenomenon is used in various scientific and technological applications, such as the diffraction grating used to separate light into its component colours in spectroscopy.

In conclusion, the bending of waves around corners is a result of the diffraction of waves. This phenomenon is a fundamental characteristic of waves and is used in various scientific and technological applications.