What's the difference between interference and diffraction?

Interference is the superposition of two or more waves, while diffraction is the bending of waves around obstacles or through openings.

Interference and diffraction are two fundamental phenomena in wave physics, particularly in the field of optics. They both involve the interaction of waves, but they occur under different circumstances and result in different outcomes.

Interference is the process where two or more waves superpose to form a resultant wave of greater, lower, or the same amplitude. This phenomenon occurs when waves from different sources coincide. The waves could either constructively interfere, leading to a resultant wave with a larger amplitude, or destructively interfere, resulting in a wave with a smaller amplitude or even no wave at all. The classic example of interference is the double-slit experiment, where light waves from two slits overlap and interfere, creating a pattern of bright and dark bands on a screen.

On the other hand, diffraction refers to the bending of waves around obstacles or the spreading out of waves through openings. This phenomenon occurs when a wave encounters a barrier or a slit that is comparable in size to its wavelength. The wave bends around the obstacle or spreads out after passing through the opening, forming a pattern of alternating bright and dark regions. This is due to the wave's parts interfering with each other after they have been diffracted. The most common example of diffraction is the pattern seen when light passes through a small aperture, such as a pinhole, and forms a circular spreading pattern.

In summary, while both interference and diffraction involve the interaction of waves, they are distinct phenomena. Interference is about the superposition of waves from different sources, while diffraction is about the bending and spreading of waves when encountering obstacles or openings. Understanding these concepts is crucial in the study of wave physics, as they underpin many optical systems and technologies.