What is the difference between interference and diffraction?


Interference and diffraction are both phenomena associated with the behavior of waves, particularly with light waves. Here are five key differences between interference and diffraction:

Definition:

Interference: Interference is a phenomenon that occurs when two or more coherent waves overlap, leading to the reinforcement or cancellation of the waves’ amplitudes at certain points in space.
Diffraction: Diffraction is the bending of waves around obstacles and the spreading of waves when they encounter an aperture or obstacle. It involves the bending of waves as they pass through openings or around obstacles.
Cause:

Interference: It is caused by the superposition of waves, where waves meet either constructively (peaks align with peaks or troughs align with troughs) or destructively (peaks align with troughs).
Diffraction: It occurs when waves encounter an obstacle or a slit, causing them to bend around the edges of the obstacle or spread out after passing through a slit.
Pattern Formation:

Interference: Interference patterns consist of regions of constructive and destructive interference, resulting in alternating bright and dark fringes.
Diffraction: Diffraction patterns typically involve the spreading of waves, leading to a pattern of alternating light and dark regions, but the specific pattern depends on the geometry of the diffracting object.
Nature of Waves:

Interference: It is typically observed in situations where multiple coherent sources of waves exist, such as with two or more sources of light or sound waves.
Diffraction: It is a general wave phenomenon that can occur with any type of wave, including light, sound, or water waves, and it is not dependent on the coherence of sources.
Conditions:

Interference: Interference requires the presence of at least two coherent sources of waves and depends on the relative phase of the waves.
Diffraction: Diffraction can occur even with a single wave source and is related to the bending of waves as they encounter obstacles or openings.
In summary, interference involves the superposition of coherent waves leading to reinforcement or cancellation, creating interference patterns, while diffraction is the bending or spreading of waves around obstacles or openings. While interference is related to the interaction of multiple waves, diffraction can occur with a single wave source.