All Questions
51
questions
0
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2
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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
47
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Most generic form of refractive index tensors
The refractive index of a material is in general a $3x3$ tensor (as in the case of birefringent crystals). From literature, it seems that in the case of transparent crystals, this tensor is in general ...
- 141
-1
votes
1
answer
78
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Inconvenience of speed of light in optic fiber
As far as I'm concerned, optic fiber is great in order to transport information quickly using light. Since light needs to undergo total internal reflection every single time it hits the walls of the ...
- 1,616
1
vote
2
answers
72
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Why total reflection happens at only 1 angle?
The critical angle can be intuitively understood by Snell's law.If the incident medium has a bigger diffraction index than the refracted medium then according to Snell's law the refracted ray will be ...
- 101
0
votes
1
answer
123
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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
1
vote
0
answers
32
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Microscopic model of complex refractive index
In my Electromagnetic Optics class, we tried to reconcile the microscopic (optical) properties of matter with its macroscopic counterparts, and one of the most challenging properties is the (complex) ...
- 1,616
3
votes
1
answer
102
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Can the refractive index of a medium be negative?(<0)
Recently I was asked in a test what would happen if the refractive index of a medium was negative. Is it possible really? The refractive index is the ratio of the speed of light in a vacuum and ...
- 41
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0
answers
31
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Phase jump at medium border with EM wave
I have been reading a book about electrodynamics and I have stumbled upon the following matter which is, to me , contradictory. When the electromagnetic wave changes medium, it is subject to certain ...
- 35
0
votes
1
answer
46
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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
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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
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votes
2
answers
53
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How to increase the angle of light (without going from a higher to lower index of refraction)?
I would like a device to spread out/increase the angle of rays in a light source. In other words, I would like to reproduce the behaviour of light traveling from an area of higher to lower index of ...
- 1
-1
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1
answer
60
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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
1
answer
398
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Deriving the focal length of a graded index lens (GRIN)
I want to find a closed expression of the focal length of a graded index since I don't manage to find any on the internet. I already checked this out: Determining the focal length of a gradient index ...
- 344
1
vote
0
answers
65
views
What are the physics behinde reflection and refraction of electromagnetic wave at a dialectric surface?
I have understood the most of the equations that lead to the Fresnel-Equations from electromagnetic waves and Maxwell equations. But not enough to understand what is happening. So I don't ask for an ...
- 11
2
votes
1
answer
65
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Analysis of the reflection in metal
In order to solve the reflexion in a material with a complex index the solution I've found on textbooks is to define $\hat{n}\cos{\phi}:=a+bi$ where $\hat{n}=n_r+n_ii$ is the complex index and then ...
- 225