What is diffraction in the context of waves?

Diffraction is best described as the phenomenon where waves spread out after passing through an opening or around obstacles. This behavior occurs because when waves encounter a gap or edge, they do not simply continue on their original path; instead, they bend and spread out in various directions. The amount of diffraction that occurs is influenced by the size of the opening relative to the wavelength of the wave. If the wavelength is comparable to the size of the opening, significant diffraction is observed.

This concept is essential in understanding wave behavior in various contexts, including sound and light waves. For example, when sound waves pass through a narrow doorway, they can be heard even when someone is standing outside—this is due to the wave's ability to spread out after passing through the opening. In contrast, options that discuss an increase in wave amplitude, absorption of wave energy, or direct propagation in a straight line don't accurately capture the essence of diffraction. Instead, they describe other wave phenomena that do not involve the characteristic spreading of waves associated with diffraction.