All Questions
Tagged with electromagnetism refraction
122
questions
85
votes
4
answers
40k
views
What is the mechanism behind the slowdown of light/photons in a transparent medium?
So light travels slower in glass (for example) than in a vacuum. What causes light to slow down? Or: How does it slow down? If light passes through the medium, is it not essentially traveling in the "...
- 1,063
16
votes
4
answers
3k
views
To what extent can speed of light be reduced? [duplicate]
Light slows down upon entering different transparent objects, and the ratio is taken as refractive index of the object. If light can be slowed down, then is there a limit up to which it can be slowed ...
- 803
15
votes
2
answers
843
views
Which of these theories on why light slows in media are true?
This question is similar to previously asked questions, but the responses to them are confusing and I think it may be better covered by listing out all the potential answers for clarity.
It's a ...
- 532
11
votes
4
answers
2k
views
How can reflection and refraction be explained classically and microscopically?
I was trying to explain something about Brewster's angle and realized I don't completely understand how reflection and refraction work on the microscopic, classical level.
Consider a plane polarized ...
- 103k
10
votes
6
answers
3k
views
Lorentz invariance of Maxwell's equations in matter
I know that Maxwell's equations of electromagnetism are Lorentz invariant in a vacuum. But what about in a generalized medium, e.g. a metal, a rubber, a dielectric, a magnet? I have read it comes down ...
- 1,087
9
votes
4
answers
520
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Mathematics supporting the classical explanation of why the phase speed of light slows down in a medium
Consider the answer here by Chad Orzel which explains how a monochromatic light can slow down in a medium. He explains,
You can think each of the atoms (of the medium) as being like a little dipole,...
- 26.8k
9
votes
4
answers
2k
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Why is the speed of light in a medium smaller than its value in vacuum?
The speed of electromagnetic waves in a medium is smaller than its value in the vacuum: $$v=\frac{1}{\sqrt{\mu\epsilon}}=c/n<c$$ with the refractive index $n=\sqrt{\frac{\mu\epsilon}{\mu_0\...
- 26.8k
8
votes
3
answers
1k
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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
8
votes
2
answers
719
views
Special Relativity, refractive index and catching up with a wave
Einstein was partially motivated by the following: With Maxwell's equations, a plane wave is a sinusoidal wave that varies in space in time and moving with speed $c$. These variations are linked by ...
- 3,856
7
votes
2
answers
2k
views
Physical explanation for why total internal reflection occurs
I have been trying to understand total internal reflection (and have read several posts on this site already). Mathematically, I feel that I understand how the evanescent wave decays exponentially as ...
- 4,608
6
votes
2
answers
61k
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Why is the index of refraction different for different wavelengths? [duplicate]
The index of refraction can be written as
$$n=\frac{\lambda_v}{\lambda_m}$$
where $\lambda_v$ is the wavelength in a vacuum and $\lambda_m$ is the wavelength in the medium. I’ve been told that since ...
- 1,499
5
votes
1
answer
241
views
EM wavelength in different medium
Considering a light wave traveling from the vacuum to air, I am trying to find what will happen to its wavelength.
At first, using optics, we know that:
$$n=\frac{c}{v}$$
where $n$ represents the ...
- 121
5
votes
3
answers
1k
views
What happens to light as it enters a denser medium?
I am a first year undergrad student doing optometry (never done any physics before in my life :( ). I got a question asking what happens when light enters a denser medium. I was told that the ...
- 51
5
votes
1
answer
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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
4
votes
2
answers
233
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Are there any real-world examples of refraction of light by magnetic permeability?
The question Fresnel Transmission Coefficient for Magnetic Field is interesting.
Thinking about it led me to reflect upon what little I know of the history of optics, with refraction by lenses and ...
- 6,273