Propagating solutions to Maxwell’s equations in classical electromagnetism and real photons in quantum electrodynamics. A superset of thermal-radiation.

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Way to measure wavelength of infrared radiation?

I am wondering if there is a device for measuring wavelengths of things. As semiconductors emit infrared radiation and I would like to know what is the wavelength it is so I can check to see if its ...
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What’s the relationship between thermal radiation and Johnson thermal noise?

All objects above absolute zero emit radiation due to random collisions between the atoms they are made of. The spectrum of radiation emitted varies according to the temperature of the object, I ...
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How can I determine transmission/reflection coefficients for light?

When light rays reflect off a boundary between two materials with different indices of refraction, a lot of the sources I've seen (recently) don't discuss the relation between the amplitude (or ...
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What causes polarised materials to change colour under stress?

Our physics teacher showed the class a really interesting demonstration. He used two polarised filters in opposite orientations, then he took some antistatic tape and stretched it under the two ...