What is the definition of diffraction?

Diffraction refers to the bending and spreading of waves when they encounter an obstacle or pass through an opening (or gap) that is comparable in size to their wavelength. This phenomenon occurs with all types of waves, including sound waves, light waves, and water waves.

When waves approach a gap or an obstacle, they do not simply continue to travel in straight lines; instead, they change direction, which gives rise to the characteristic spreading pattern that can be observed. This behavior is particularly noticeable when the size of the barrier or gap is similar to the wavelength of the waves, effectively demonstrating how waves can interact with the physical environment around them.

This understanding of diffraction helps explain many physical phenomena, such as the patterns formed by light waves passing through narrow slits or the way sound can be heard even when the source is not in direct line of sight.