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Refraction of light

by wellorderingp
Tags: light, refraction
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jtbell
#19
Jul22-14, 06:18 AM
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Quote Quote by DrDu View Post
1. Is it possible to build a light detector which measures wavelength and not frequency?
In a Michelson interferometer, moving one of the mirrors through a distance λ/2 changes the path length of that "arm" of the interferometer by λ and causes the interference pattern to shift by one cycle.
sophiecentaur
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Jul22-14, 06:33 AM
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Quote Quote by DrDu View Post
1. Is it possible to build a light detector which measures wavelength and not frequency?
A broadband detector (which doesn't care about frequency), in conjunction with any form of interference generating structure - like a diffraction grating (or a prism, of course) will tell you the wavelength of the light reaching it and within the wavelength measuring device. It will tell you nothing about the wavelength of the light on its path to the detector. It could have passed through glass, water, vacuum etc. etc. but would not show anything of this history - just its frequency.
Take a calibrated diffraction grating and operate it under water (quite possible to do). It will still give you a value for the wavelength it measures - but the frequency of the light will not correspond to that wavelength in air.

We seem to have done all the possible combinations in this thread. Surely the main message is that

c = fλ
where c can vary with the medium.
??


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