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Physics, Astronomy & Cosmology / Re: why do a lot of people confuse between interference and diffraction?
« Last post by hamdani yusuf on Today at 15:45:46 »Feynman has come from heaven to answer your question! Listen to him:IMO, the confusion came from the lack of willingness and courage of science communicators and educators to make corrections when the errors were made by prominent or famous people that they highly respected. The quoted statements don't seem to reflect what Feynman believed to be the correct definitions of diffraction and interference, but rather an observation of how people in his time used those words.
No one has ever been able to define the difference between interference and diffraction satisfactorily. It is just a quest of usage, and there is no specific, important physical difference between them. The best we can do is, roughly speaking, is to say that when there are only a few sources, say two interference sources, then the result is usually called interference, but if there is a large number of them, it seems that the word diffraction is more often used.1
To be more explicit read this passage from Ajoy Ghatak:
We should point out that there is not much of a difference between the phenomenon of interference and diffraction, indeed, interference corresponds to the situation when we consider the superposition of waves coming out from a number of point sources and diffraction corresponds to the situation when we consider waves coming out from an area sources like a circular or rectangular aperture or even a large number of rectangular apertures (like the diffraction grating). 2
Credits: 1 Feynman Lectures on Physics 2Optics-Ajoy Ghatak.