All Questions
Tagged with electromagnetic-radiation energy
30
questions with no upvoted or accepted answers
4
votes
3
answers
164
views
Origination of electromagnetic wave energy
Please correct me if I am wrong in my statements
While it is said that electromagnetic waves are formed by the oscillation (acceleration) of charges which forms 'kinks' in their electric field which ...
- 87
2
votes
1
answer
36
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Why don't the delocalised electrons in a metal emit light when they hit an atom and change their velocity very quickly (i.e. accelerate)
We know that in metals there is a sea of delocalised electrons which can freely travel around the lattice of metal ions and that these delocalised electrons move around at large speeds, sometimes ...
- 531
2
votes
2
answers
207
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Does the formula $E = hf$ apply to all electromagnetic waves?
The formula $E=hf$ shows the energy contained in one photon. Here, we use the simple half wave dipole antenna to evaluate the energy of photons at different frequencies. Surprisingly that gives a ...
- 31
2
votes
0
answers
70
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Frequency Spectrum and Energy of an electromagnetic impulse
The energy associated with an electromagnetic wave, in its simplest form, is given by the relation:
$$ E = h\nu $$
Where $h$ is Planck's constant. However, this energy relates to a definite frequency. ...
- 198
1
vote
0
answers
17
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Will an electron release energy when it is added into an atom for which electron affinity value is negative (endothermic)?
According to my understanding, when an electron is added into an atom, it emits energy in the form of photons because it is a form of de-excitation or relaxation. This is when electron affinity will ...
- 11
1
vote
1
answer
32
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Absorption and emission spectrum
I was wondering how do you see a spectrum when light is passed through a substance. Like most of the substances we use are opaque, so how does light pass through them without being reflected? Also ...
- 11
1
vote
0
answers
16
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Does a standing wave on a path have different free energy than a traveling wave?
My somewhat naïve view is that the standing wave is "bound" to its path, and thus higher in free energy than a traveling wave of equivalent amplitude and wavelength. But I'm not sure how ...
- 57
1
vote
0
answers
47
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Radiation from a moving charge particle in expanding universe?
Moving charged particles generally emmit energy in form of radiation.
Assume a charged particle that is situated in a zone that can join the Hubble flow and therefore starts moving away from us.
As it ...
- 2,462
1
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0
answers
26
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How do you determine the number of ejected electrons based on the photon flux?
If you have a light source with a frequency higher than a materials Electron binding energy, what percent of the photons will eject electrons?
- 4,083
1
vote
1
answer
312
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How to get the formula of the energy of EM waves?
I am trying to get the formula for energy of EM waves:
$$W = \frac{E^2 + B^2}{2}$$ calculating the work done on a test charge by the force: $$\mathbf F = q(\mathbf E + v \times \mathbf B)$$ $\mathbf ...
- 16.7k
1
vote
0
answers
16
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Does a laser's listed wattage or joules include the frequency? Or just the amplitude?
In other words, if the number of photons in two different lasers is the same, but the second laser has a higher wavelength, does the second one have more 'wattage' or more total joules?
(Since higher-...
- 4,509
1
vote
1
answer
106
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How does light energy increase when passing through the ergo sphere of a black hole?
I watched a video recently about using the ergosphere of a spinning black hole as a source of virtually infinite energy by surrounding it with mirrors and shining electromagnetic waves in there. In ...
- 11
1
vote
1
answer
65
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Energy-frequency dependency of a photon and its medium of propagation
Is the equation relating a photon's energy to its frequency the same regardless of its medium of propagation? And for the equation relating its momentum to wavelength as well?
- 11
1
vote
0
answers
302
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Intensity of monochromatic propagating wave in terms of electric field amplitude
I'm looking at the (local) intensity of an MC propagating wave in terms of the electric field and I found something pretty good:
\begin{equation}
\left|E\right|^2 = \frac{2I}{\epsilon_0 c}.
\end{...
- 298
1
vote
0
answers
67
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Is it possible in this Universe to communicate a bit of information with energy that scales sub-linearly with distance?
If we look at all the ways that people do communicate information, they all seem to have a cost "at least linear in distance." For example, communicating over a wire has attenutation, so the energy ...
- 11