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Physics, Astronomy & Cosmology / Re: why do a lot of people confuse between interference and diffraction?
« on: 28/12/2022 15:59:52 »
Hi.
Now just some basic tests to see if everyone really has thought this through:
When monochromatic light passes through a single slit and produces a pattern on a screen. What do you call that pattern on the screen?
(a) A diffraction pattern. (Note that Feynmann suggested diffraction applies only for multiple sources interacting. However, light does spread out when passing through a slit, I mean this single slit thing is the text-book example of a diffraction process isn't it?).
(b) An interference pattern. (Can you have interference with one source of light? Yes you can and you do @alancalverd whenever that light passes through an aperture).
When monochromatic light passes through two slits and produces a pattern.... What do you call that?
(a) A diffraction pattern.
(b) An interference pattern.
When ...light ... passes.... diffraction grating... screen. What do you call that?
(a) A diffraction pattern. (I mean, it had the name "diffraction" in "diffraction grating" didn't it?)
(b) An interference pattern. (Feynmann suggestion is that you really should be calling this diffraction by now).
I think common usage of the terms would have the answers a (for 1 slit), b (for 2) then back to a (for diffraction grating). @hamdani yusuf asked about school pupils and what they are taught in schools. I've just spent 20 minutes going through the AQA syllabus for physics at "A" level. They do describe the patterns with these terms.
Meanwhile the Feynmann suggestion should give b, b, a.
If I've got the gist of what @hamdani yusuf wants the definitions of diffraction and interference to be. (One is about bending light, the other includes producing bright and dark bands in a pattern) then the answers are b, b, b.
My view is... what the figgy pudding does it matter?
Best Wishes.
Now just some basic tests to see if everyone really has thought this through:
When monochromatic light passes through a single slit and produces a pattern on a screen. What do you call that pattern on the screen?
(a) A diffraction pattern. (Note that Feynmann suggested diffraction applies only for multiple sources interacting. However, light does spread out when passing through a slit, I mean this single slit thing is the text-book example of a diffraction process isn't it?).
(b) An interference pattern. (Can you have interference with one source of light? Yes you can and you do @alancalverd whenever that light passes through an aperture).
When monochromatic light passes through two slits and produces a pattern.... What do you call that?
(a) A diffraction pattern.
(b) An interference pattern.
When ...light ... passes.... diffraction grating... screen. What do you call that?
(a) A diffraction pattern. (I mean, it had the name "diffraction" in "diffraction grating" didn't it?)
(b) An interference pattern. (Feynmann suggestion is that you really should be calling this diffraction by now).
I think common usage of the terms would have the answers a (for 1 slit), b (for 2) then back to a (for diffraction grating). @hamdani yusuf asked about school pupils and what they are taught in schools. I've just spent 20 minutes going through the AQA syllabus for physics at "A" level. They do describe the patterns with these terms.
Meanwhile the Feynmann suggestion should give b, b, a.
If I've got the gist of what @hamdani yusuf wants the definitions of diffraction and interference to be. (One is about bending light, the other includes producing bright and dark bands in a pattern) then the answers are b, b, b.
My view is... what the figgy pudding does it matter?
Best Wishes.
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