How does wavelength affect a wave's ability to diffract?

The wavelength of a wave significantly influences its ability to diffract, with longer wavelengths diffracting more than shorter ones.

Diffraction refers to the bending of waves around obstacles or the spreading of waves after they pass through a gap. This phenomenon is a fundamental characteristic of waves, including light, sound, and water waves. The degree of diffraction, or how much the wave spreads out, is directly related to the wavelength of the wave and inversely related to the size of the obstacle or gap.

The longer the wavelength, the more a wave tends to diffract. This is because diffraction is a result of the interference of the wave with itself. When a wave encounters an obstacle or a gap, it splits into several secondary waves. These secondary waves then interfere with each other, creating a pattern of constructive and destructive interference. The longer the wavelength, the greater the distance between these secondary waves, and thus the greater the degree of diffraction.

For example, consider a wave passing through a gap. If the wavelength is much smaller than the size of the gap, the wave will pass through with little diffraction. However, if the wavelength is comparable to or larger than the size of the gap, the wave will diffract significantly. This is why low-frequency (long wavelength) sounds can be heard around corners, but high-frequency (short wavelength) light cannot.

In the context of light, this principle explains why different colours of light diffract by different amounts when they pass through a prism. Red light, which has a longer wavelength than blue light, diffracts more and is therefore bent more by the prism. This results in the familiar rainbow spectrum produced by a prism.

In summary, the wavelength of a wave plays a crucial role in determining its ability to diffract. Longer wavelengths result in greater diffraction, allowing the wave to bend around obstacles and spread out after passing through gaps. This principle is fundamental to our understanding of wave behaviour and has important implications in various fields, from acoustics to optics.