All Questions
17
questions
-1
votes
1
answer
78
views
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
74
views
On the (variable?) nature of $\epsilon_0$ and $\mu_0$
In electromagnetism, the electric displacement field D represents the distribution of electric charges in a given medium resulting from the presence of an electric field E. Its relation to ...
- 115
3
votes
1
answer
102
views
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
1
vote
2
answers
104
views
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 ...
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
1
vote
4
answers
214
views
How can the speed of light in matter be measured?
Experiments such as Focault's measure speed of light in matter. Focault's experimental set-up is based on the idea that it takes more time for light to travel through matter, which will result in the ...
- 1,171
0
votes
2
answers
131
views
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
4
answers
118
views
About the lowering of the speed of light in non-vacua
I don't understand really why matter interacts with light so as to slow down wavefronts to a speed strictly below $c$, but still preserving that sharp wavefront-like signal.
This is somewhat ...
- 643
2
votes
2
answers
2k
views
If different wavelengths of light have different speeds, how can they move together as a white light in air?
My question is with respect to Newton's experiment of using two identical glass prisms [in which one is inverted with respect to the first one]. When he allowed all the colors of the spectrum to pass ...
0
votes
6
answers
2k
views
Could the refractive index of a material change?
Is it possible that the refractive index of a material could change? If so, what are those factors and what kind of variation could they bring?
9
votes
4
answers
2k
views
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
-1
votes
1
answer
1k
views
Are images formed due to reflection or refraction and what do we see? HOW?
I am getting extremely confused about what we see as individuals : do we see reflected rays or refracted rays and what does our brain interpret?
The concept has bewildered me for a long time. Googling ...
user116688
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
0
votes
1
answer
709
views
How is light slowing down in a medium thought of in the photon picture? [duplicate]
The speed of light in any medium besides vacuum is smaller than $c$. In a classical way, I just look at that as a wave that propagates less fast, the change in EM-field is passed on slower. How should ...
- 1,004