All Questions
Tagged with electromagnetic-radiation photons
66
questions with no upvoted or accepted answers
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Do photons form bound states?
Since photons do not have electric charge, they do not interact via the electromagnetic force. They are also reported to be devoid of any colour-charge, so interaction via the strong force is ruled ...
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How is magnetic flux viewed in QED?
I know that QED is formulated in terms of Lagrangian density. So when we solve for a physical system we ultimately ends up finding $\psi$ and $A_{\mu}$. I'm not interested in $\psi$ for now. Since I ...
- 3,043
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An accelerating charge emits EM waves, but how can this be explained in terms of photons?
I was reading this response to a question involving EM radiation due to an accelerating charge. A charge's oscillations disturb its electric field, and this effect propogates at the speed of light. If ...
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Link between photon helicity and polarization of $A^\mu$ electromagnetic potential
From Wigner theorem we know that the irreducible unitary representation of the Poincarè group for massless and spin 1 particle is labelled by the momentum $p_\mu$ and the two possible helicity $+1,-1$ ...
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Does a plasma with plasma frequency $\omega_p$ generate photons of the same frequency?
I know that photon emission in plasma results in a change of energy level of the electrons from excited or ionised atoms. However, I saw that photons of 13eV were created in a helium plasma, but this ...
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Intensity of Compton scattering photons
In various sources (1, 2, 3, 4, to name a few) I have seen this graph shown below, that shows how intensity depends on the wavelength of the scattered photon $\lambda'$.
Now, I do understand what ...
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Work done by radiation on an electron
I'm studying quantum mechanics (already done with relativity) and I'm trying to understand the matter-radiation interactions. It's said everywhere that matter emits or absorbs photons but nowhere it's ...
- 97
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Emissions from a Blackbody and the UV Catastrophe
Recently I found myself becoming confused over a topic that I thought I had previously understood.
In a theoretical blackbody which reaches thermal equilibrium the energy absorbed is equal to the ...
- 207
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What force causes light to reflect off a surface?
Since $\vec F=d\vec p/dt$ and light consists of photons which experience a change in their momentum when they are reflected off a surface it follows that some force must act on those photons at the ...
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Must a photon ever be thought of as 3-dimensional
I am still (ref. my previous questions) trying to understand the nature of photons, so here goes: It seems most physicists imagine the photon as a wave packet, which can be mathematically constructed ...
- 1,302
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Why call it a particle and not a wave pulse?
My physics textbook says that photoelectric emission provides conclusive evidence for the particle theory of light. Apparently, since photoelectric emission only works at certain frequencies, we can ...
- 562
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Single photon detection
Consider a thought experiment where we have a source emitting a single photon, like an atom/molecule going from an excited energy state to its ground state.
We have an infinite number of point ...
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Photon emission rate frequency dependency
I am puzzling over the dependence of the energy flux of electromagnetic radiation on the frequency of the source.
The power radiated in any direction or solid angle from a charged particle ...
- 1,030
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Integrating Planck's relation
By Planck relation, we know that an energy of a single photon is $E = hf$.
If we are given EM-waves with interval of frequency $f_1$ to $f_2$, does integrating from
$\int_{f1}^{f2} Edf$ $=\int_{f1}^{...
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Feynman's view about light
Professor Feynman, in his “QED: The strange theory of light and matter”, states at page 15:
“I want to emphasize that light comes in this form - particles. It is very important to know that light ...
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