How does a wave's frequency affect its diffraction?

A wave's frequency affects its diffraction in that higher frequencies diffract less than lower frequencies.

In more detail, diffraction 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 wavelength of the wave is comparable to the size of the obstacle or gap. Frequency and wavelength are inversely proportional, meaning that waves with higher frequencies have shorter wavelengths and vice versa. Therefore, waves with higher frequencies, which have shorter wavelengths, will diffract less than waves with lower frequencies, which have longer wavelengths.

This is because the degree of diffraction depends on the ratio of the wavelength to the size of the obstacle or gap. If the wavelength is much smaller than the size of the obstacle or gap, the wave will not diffract significantly and will mostly continue in a straight line. On the other hand, if the wavelength is comparable to or larger than the size of the obstacle or gap, the wave will diffract more and spread out after passing the obstacle or gap.

For example, consider light waves, which are part of the electromagnetic spectrum and have much higher frequencies (and therefore shorter wavelengths) than sound waves. When light waves encounter a small obstacle or gap, they do not diffract significantly and mostly continue in a straight line, which is why shadows have sharp edges. In contrast, when sound waves, which have lower frequencies and longer wavelengths, encounter an obstacle or gap, they diffract more and spread out, which is why you can still hear sounds even when they come from behind an obstacle.

In summary, the frequency of a wave significantly influences its diffraction. Higher frequency waves, with their shorter wavelengths, diffract less than lower frequency waves with their longer wavelengths. This principle is fundamental in understanding various phenomena in physics, such as the behaviour of light and sound waves.