All Questions
Tagged with electromagnetic-radiation wavelength
207
questions
13
votes
7
answers
2k
views
Why does the length of an antenna matter when electromagnetic waves propagate perpendicular to the antenna?
The optimum length for a dipole antenna is a multiple of half the wavelength that it is designed to receive or emit. Why is this? If an electromagnetic wave has E in the x-axis, B in the y-axis, and ...
- 141
11
votes
4
answers
2k
views
Can the laser light, in principle, take any wavelength in the EM spectrum?
Can the laser light, in principle, take any wavelength in the EM spectrum? I don't think there is what prevent this in principle, right?
- 959
8
votes
4
answers
2k
views
How can photons interact with nuclei?
How can photons such as X-rays or gamma rays interact with the nuclei of atoms given that, as I understand it, the length scale of a nucleus is around a couple of femtometers? So, shouldn’t the size ...
- 133
2
votes
0
answers
30
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Why does oxygen green (S1) emission in aurorae only occur at lower altitudes? [duplicate]
Aurorae have a red color at high altitudes caused by the excitation of atomic oxygen and the subsequent emission at about $630 \,\text{nm}$. This happens at high altitudes because at that height there ...
- 81
7
votes
5
answers
14k
views
Light waves can't have a wavelength
The wave nature of light comes from Maxwell's equations. More precisely, the two wave equations that come from them:
$$\Delta\vec{E}=\mu\varepsilon \frac{\partial^2\vec{E}}{\partial t^2}\\
\Delta\vec{...
- 267
1
vote
2
answers
52
views
Minimum frequency for a dipole antenna to work
Does a dipole antenna need a minimum frequency of AC to make the electric field detach and propagate?
- 156
1
vote
1
answer
40
views
How is wavelength defined when it's changing continuously?
Take an observer, who is receiving an electromagnetic wave signal, which is constantly changing. It can be for example from a source of light falling into a black hole, so the observed wavelength is ...
- 13
0
votes
1
answer
44
views
Emission spectrum of a fluorescent lamp
I had to analyze the emission spectrum of a compact fluorescent lamp and find what elements are present in the lamp, based on the spectrum of spikes in wavelengths. Knowing that in our lamp there was ...
-1
votes
2
answers
80
views
What's the difference between the different kinds of EM waves?
I am an A-level student.
We have traditionally been taught that different types of EM waves exist only between certain ranges of wavelengths and frequencies.
However, I learned that electromagnetic ...
1
vote
1
answer
61
views
In Rayleigh-Jeans radiation law, why are the values of $n$ taken to be non-positive only?
In $k$-space the allowed values for standing waves in a cube of side length $L$
are given by
$$\vec{k} = \left(\frac{\pi}{L}\right) (n_1, n_2, n_3)$$
where the $n_i$ are nonnegative integers. Why are ...
- 11
1
vote
1
answer
25
views
Spectroscopy on colored flames
When observing colored fire through a spectrometer after adding substances like copper chloride or magnesium sulfate to change its color, what specific spectra are typically observed? How does the ...
- 43
0
votes
1
answer
38
views
What determines the wavelength in absorption?
When looking at absorption or reflectance spectra, say in the range of 400nm to 2500nm, you can see peaks (or dips) at certain wavelengths, that are characteristic for the material absorbing and ...
- 111
15
votes
6
answers
7k
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Why color depends on frequency and not on wavelength? [duplicate]
To explain my question lets consider this example:
The wavelength of light in a medium is $\lambda=\lambda_{0}/\mu$, where $\lambda_{0}$ is the wavelength in vacuum. A beam of red light ($\lambda_{0}=...
- 2,517
2
votes
2
answers
94
views
Does gravitational lensing bend light of all wavelengths by the same amount?
Basically I am asking if gravitional lensing is bending or refracting light.
- 319
0
votes
1
answer
88
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What is the wavelength range of X-rays?
I was reading and came across the following paragraph
The X-rays thus produced by many electrons make up the continuous spectrum of Figure 2-10 and are very many discrete photons whose wavelengths ...
- 959