All Questions
Tagged with electromagnetic-radiation wavelength
22
questions with no upvoted or accepted answers
2
votes
2
answers
835
views
Why do small particles deferentially scatter colors (i.e scatter more blue light than red in Rayleigh scattering) while larger particles don't?
In both small and large particles, light as an EM wave will accelerate charged particles such as electrons and induce a dipole forcing the electrons to oscillate at the same frequency of incident ...
2
votes
0
answers
28
views
What are upper reflectivity bounds of materials
I know that if i take metal-coated fiber i can send light signals to large distance, because signal would reflect inside fiber, lowering attenuation. Just like in optical fiber communication network. ...
- 183
2
votes
2
answers
84
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Which metals are suitable to make structures in GHz and THz applications?
In GHz applications, Cu is mainly used to make structures and in THz applications Al or Au is used to make structure. Is there a special reason to use these metals in particular wavelengths?
- 21
1
vote
1
answer
4k
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Converting between $F_{\nu}$ and $F_{\lambda}$ spectral density
In papers, spectral energy distributions are given either in $F_\nu$, $\nu F_\nu$, $F_\lambda$ or $\lambda F_\lambda$.
$F_\nu$ has units of Janskys, for example.
Is there a clear explanation online I ...
- 181
1
vote
3
answers
262
views
Zero-dispersion wavelength
Please help me understanding the zero-dispersion wavelength in fibers.
I found this wiki-article on the topic. Accordingly:
"In a single-mode optical fiber, the zero-dispersion wavelength is the ...
- 113
1
vote
0
answers
416
views
Does reflection depend on wavelength?
I'm aware of processes like Rayleigh scattering, Compton scattering and pair production. But as these processes treat light as being particles(?) I'm not sure whether they are helpful to understand ...
- 1,507
1
vote
0
answers
53
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Does the Planck length imply that the smallest different between any two wavelengths must also have a limit?
I was looking at a video called How Hot Can It Get, and at 7:08, the host Michael states that
if an object were to reach a temperature of $1.41 \times 10^{32}$ K (planck temperature), the ...
- 509
1
vote
1
answer
155
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Planck theory of discrete energy of photons and electromagnetic spectrum
Planck said that "energy of photon is quantized. That means energy of a photon cannot be any random value but a certain values only".
If this is true how electromagnetic spectrum is continuous. For ...
1
vote
0
answers
96
views
What wavelengths of electromagnetic radiation are emitted by the LH2/LOX reaction?
Rocket engines such as the Rocketdyne Rocket System 68 and the Space Shuttle Main Engine use liquid hydrogen and liquid oxygen as propellants. The exhaust from this type of engine is notable in ...
0
votes
0
answers
34
views
Wavelength in Multiple Lossy Layers
I would like to derive an equation for the wavelength of a plane electromagnetic wave (normal incidence) in each layer of a multilayered lossy medium, as shown below.
Which equations are required for ...
- 11
0
votes
1
answer
66
views
How to correctly understand wavelength of EM waves?
When we mention wavelength of EM waves, does the wavelength mean vacuum wavelength?
Is the frequency of every scalar component (x, y and z) $c/λ$, no matter whether it's linearly, elliptically or ...
- 69
0
votes
0
answers
77
views
EM scattering cross section, antenna directivity and its interpretation
The formula (35.25), see Slater, $\bar A_r = \frac{\lambda^2}{4\pi}$ is probably the most important formula in radar and/or antenna engineering. It says that the average absorbing cross section of ...
- 19.8k
0
votes
0
answers
105
views
Why half-wave dipole is the most efficient one in comparison to other electrical lengths?
I have a problem on the understanding of a half-wavelength antenna. Namely, why is the half-wave antenna has a highest power emission. Considering Far Field factor F($\theta$), which is known from the ...
- 591
0
votes
0
answers
91
views
Walkie talkie antenna
how is it possible that the antennas of the walkie talkies are so small, if the frequencies they receive have wavelengths of more than 30 cm? Maybe the why's are quarter wave antennas? and for pulsed ...
- 11
0
votes
0
answers
36
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Changes to an EM-wave that is propagating in an inflating space
I am trying to get an easier picture of what happens to an em-wave considering space expansion. My question is: If a star in a non-inflating space emits light recorded at a certain distance of the ...
- 1,815