All Questions
28
questions
0
votes
2
answers
123
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Diffraction when the wavefront is not parallel to the plane
I am studying Feynman's chapter on the origin of the index of the refractive index (see this link).
If I am not mistaken, what he does is to prove that when a wave enters a medium (modelled as a ...
- 507
0
votes
1
answer
46
views
Help with dispersion relations for EM waves in anisotropic dielectric materials
I am really struggling to understand the following dispersion relations which we derived in class.
For an electric field in the z-direction, we have:
$$k^2_x + k^2_y = \frac{\omega^2}{c^2}n_z^2\tag{1}$...
- 155
0
votes
2
answers
66
views
How to use the boundary conditions of electromagnetic waves to derive the refraction law of light?
In my book it says we can use the boundary conditions of electromagnetic waves to derive the refraction law of light. How to derive it?
- 353
2
votes
0
answers
45
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Photon energy-momentum relation inside a material [duplicate]
I understand that the speed of light in a medium like glass, $c_n$, is reduced by the refractive index $n$ so that we have:
$$c_n=\frac{c}{n},$$
where $c$ is the speed of light in the vacuum.
Is it ...
- 5,925
1
vote
2
answers
104
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Speed of EM Waves
We know that for electromagnetic waves, according to Maxwell's Theory
$$v=\frac{1}{\sqrt{\mu\epsilon}}$$
Now consider an opaque object like say Gold. It has a particular value of permittivity and ...
-1
votes
1
answer
60
views
Do any of the color bands in a rainbow contain an electrical charge relative to clouds that might explain a photo of lightning striking a rainbow?
Caveat: While I am not a physicist myself, I am extremely interested in physical phenomena. I am well versed in electrical theory, and I am aware of the attraction between the bottoms of clouds and ...
1
vote
0
answers
57
views
Decoherence of a laser beam via oil emulsion
This is sort of a followup to an earlier question that I posted regarding how to destroy the temporal and/or spatial coherence of a laser beam. It was suggested to me that I could use a rapidly ...
- 366
1
vote
2
answers
277
views
Is there a wave equation describing electromagnetic waves in materials?
Solutions to the usual wave equation for electromagnetic waves have the property that wave components of different wavelengths travel at the same phase speed $c$, so no dispersion occurs.
What I ...
- 8,640
0
votes
0
answers
105
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Why is the refractive index $n$ linked to the wavevector $\hat{n}$?
Preamble: I'm studying light-light scattering in Effective QED but I notice that I don't remember a single thing from my EM/Optics courses so I decided to review some things.
Question: why is the ...
- 5,931
8
votes
3
answers
1k
views
Why does the wave velocity of EM signals in a wire depend on the insulator's permittivity?
I'm in an electromagnetism class and struggling with a concept. The textbook derived several equations which state that the wave velocity of an electrical signal in a transmission line depends on the ...
- 205
0
votes
2
answers
131
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Are there materials that just change the speed of light?
Maxwell's equations in medium without charges read
\begin{align}
0&=\nabla\cdot D\,,\\
0&=\nabla\cdot B\,,\\
0&=\nabla\times E + \dot B\,,\\
0&=\nabla\times H - \dot D\,.
\end{align}
...
- 1,291
1
vote
0
answers
54
views
In anisotropic media, is there a speed of light tensor like there is a refractive index tensor?
Lets say we have an homogeneous anisotropic medium where $\tilde\mu_r=\tilde\epsilon_r$ so we don't have to worry about polarization effecting anything. As such, the refractive index can be simply ...
- 780
1
vote
3
answers
2k
views
Are the amplitudes of the electric field and the magnetic field of an electromagnetic wave equal?
In an electromagnetic wave, is the maximum amplitude of the electric field the same as that of the magnetic field? I ask this question which may seem silly because on all the diagrams representing an ...
2
votes
4
answers
453
views
How we can explain bending of electromagnetic waves in a different optical media?
How can we explain the bending of light when it moves through different optical media by Maxwell's equations treating light as an electromagnetic wave?
5
votes
1
answer
1k
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Are Fresnel Equations with Complex Indices and Angles always valid?
This question-answer pair came after i was asked the following question and realized i had to do some research of my own to answer it fully, and to be sure that the answer is „yes“, in the sense ...
- 88.5k