All Questions
Tagged with refraction dielectric
28
questions
2
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0
answers
26
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Definition of the displacement field in classical field Lagrangian
In a BSM related paper (in appendix B), the authors use an effective Lagrangian $\mathcal{L}_{EFT}$, and define the following fields:
$$ \mathbf{D} = \frac{\partial\mathcal{L}_{EFT}}{\partial\mathbf{E}...
- 143
0
votes
1
answer
119
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Wave propagation in inhomogeneous media
There is a problem I'm trying to solve for some time now and is about the standard (?) approximation that it is made when one tries to solve the Helmholtz equation in inhomogeneous media, that is
\...
- 11
3
votes
2
answers
132
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Why is $c = \frac{1}{\sqrt{\mu_0 \epsilon_0}}$?
I'm sorry if this is a duplicate but I didn't find my answer. I'm currently studying maxwell's equations and I know that by comparing the wave equation for either the magnetic or the electric field
\...
- 33
0
votes
1
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83
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Why does the relative permittivity of Sapphire not match the square of its refractive index?
According to the Wikipedia, the refractive index of sapphire is around $n = 1.8$ while its relative permittivity $\varepsilon_{\mathrm r}$ is between $9$ and $11$ (depending on the direction). Given ...
- 329
1
vote
1
answer
112
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Where can I find tables of the refractive index (real and complex part) or dielectric function as a function of frequency for different materials?
I need this information to do simulations for my master's thesis but I don't know if there is a bibliography or a repository on the internet with this information. They are simple materials, water, ...
1
vote
1
answer
29
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Planck radiation law of a dielectric layer
Suppose we have a rectangular slab of thickness $h$, width $a$ and length $b$. The upper surface of the slab is put at constant temperature $T$ while all the rest is at initial temperature $T_0$. ...
- 593
1
vote
1
answer
172
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The difference between the equation of Permittivity and Permeability in a medium
I notice that the equations of Permittivity and Permeability in a linear medium are exactly opposite of each other. One is $$\mathbf{D} \equiv \varepsilon \mathbf{E}$$ while the other one is $$\mathbf{...
- 11
4
votes
2
answers
697
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Intuitive meaning of the permittivity and the permeability in Electromagnetism
I wonder what the correct way to intuitively understand the concepts of electrical permittivity and magnetic permeability would be.
The electric permittivity $\varepsilon$ of a medium is defined as a ...
- 974
2
votes
1
answer
203
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Reflectivity coefficients at dielectric interface
In the book Principles of Lasers by Orazio Svelto, at chapter 4.3 "Wave Reflection and Transmission at a Dielectric Interface", the author tells that
If the wave is initially in the medium ...
- 1,894
3
votes
0
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73
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Time lag between observed electrical field and polarity of light?
I was listening to the Feynman lectures on physics Vol. 3, Ch.2 the other day, and he was talking about the relationship between light polarity and the electric field of light as it is transmitting ...
- 361
0
votes
1
answer
276
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Highest refractive index dielectric
What is the material or metamaterial that is a very good dielectric and has a very high refractive index at least in frequencies below $500\ MHz$?
- 119
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votes
1
answer
1k
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Dielectric constant change in the atmosphere?
I'm curious about the refractive index changing in the atmosphere. As I understand it (and I may very well be wrong/naive) when a ray of light enters from one medium into another, the electric field ...
- 90
1
vote
1
answer
200
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Why can't $ε_r<1$ (at low frequencies)?
I've heard it said that the vacuum permittivity is the lowest possible permittivity for any substance, that no substance can have $ε_r<1$. Is this true? If so, why is this different from ...
- 389
2
votes
2
answers
1k
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Maxwell's equations, nonlinear media, and dynamic response
Maxwell's equations in the vacuum with electric permittivity $\epsilon_0$ and magnetic permeability $\mu_0$ are given as:
$$\nabla \cdot \vec E = \frac{\rho}{ \epsilon_0}$$
$$\nabla \cdot \vec B = 0$...
- 24.8k
19
votes
1
answer
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How can the refractive index be below 1 in a dielectric?
Upon checking the optical properties of different dielectrics, I found the interesting case of $Al_2O_3$. It seems to be reported with a refractive index below 1 in the infrared range of $10 - 12~\mu ...
- 4,788