In the context of a single slit, the phenomenon that occurs is primarily diffraction rather than wave interference. Diffraction refers to the bending and spreading out of waves as they encounter an obstacle or pass through an aperture (an opening).
When a wave, such as light or sound, passes through a single slit, it diffracts and spreads out on the other side of the slit. This spreading out of the wave is due to the interaction of the wave with the edges of the slit. The diffracted wave exhibits a pattern of alternating bright and dark regions on a screen placed behind the slit, known as the single-slit diffraction pattern.
In this case, the diffraction pattern arises from the wavefronts of the wave spreading out in a circular or semicircular manner from the slit. The spreading out of the wavefronts is responsible for the observed pattern of intensity distribution on the screen.
Interference, on the other hand, refers to the interaction of multiple waves with each other, resulting in constructive or destructive interference. In the case of a single slit, there is no interaction between multiple waves that leads to interference effects. The pattern observed in a single-slit diffraction experiment is a result of the diffraction of the wave passing through the single slit.
It's worth noting that in certain cases, such as when the width of the slit is comparable to the wavelength of the wave, interference effects can become more prominent and contribute to the observed diffraction pattern. This is known as the Fraunhofer diffraction regime, where interference effects can be observed alongside diffraction. However, even in these cases, the term diffraction is still commonly used to describe the overall phenomenon.