All Questions
Tagged with refraction speed-of-light
216
questions
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
0
votes
1
answer
82
views
Can we slowdown speed of photons? [closed]
Can we slowdown speed of photons or light? If we slowdown the speed of photon can photon give us mass?
0
votes
0
answers
26
views
How refractive index is related to speed of light in mediums? [duplicate]
Snell's law tells us that,
Sine of angle of incident of light by sine of angle of refraction of light, when light travels from one medium to other, is a constant(for that mediums).
It is also related ...
- 662
1
vote
1
answer
304
views
Calculating time of flight given index of refraction as a function of depth
Calculating light speed given a simple index of refraction is trivial, of course ($n = \frac{c}{v}$).
I'm not sure, however, how one would calculate the 'time of flight' for a light signal in a medium ...
- 799
15
votes
6
answers
6k
views
Why are red and blue light refracted differently if they travel at the same speed in the same medium?
When I look at Snell's law
$\frac{\sin\theta_2}{\sin\theta_1} = \frac{v_2}{v_1} = \frac{n_1}{n_2}$
I don't see any reference to wavelength.
If red and blue have the same speed in the same medium, why ...
2
votes
2
answers
63
views
Can light take a (faster) detour?
I was taught that light tends to take the 'fastest' route. However, this made me wonder about the following scenario:
Suppose the start and end point (source and observer) are at the edge of a large ...
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
0
votes
1
answer
171
views
In what media the speed of light is slower than the speed of radio waves, if any?
In what media the speed of visible light is slower than the speed of radio waves, if any?
Particles can be faster than visible light, but other electromagnetic waves?
63
votes
3
answers
4k
views
In substances where light is slowed down, is its momentum lessened and if so, how does it speed up again when emerging from that substance? [duplicate]
I think in some media, light can be significantly slowed down; but even if only slightly, where would the momentum go when the light slows down and where does it get the extra momentum when it leaves ...
- 2,238
3
votes
3
answers
1k
views
Can an object move faster than the speed of light in a medium? [duplicate]
In water the speed of light changes to $2.25 \cdot 10^8m/s$. Can a electron travel faster/travel at the same speed in water. I don't see any violation of SR. So shouldn't it be possible for an ...
- 1,333
1
vote
0
answers
23
views
Is it possible to simulate a high index of refraction
I am trying to demonstrate the effect of index of refraction on light speed to a high school class. As with all adolescents, if a story does not have extreme impact, it does not register (hence the ...
- 1,721
4
votes
1
answer
650
views
Does phase velocity or group velocity change when light enters a new material? Contradictory sources
I'm so confused. I've read in this book (page 28) that group velocity of light can exceed $c$ in certain gases. However a lot of people online and in the forums say that phase velocity can exceed $c$.
...
- 143
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
1
vote
0
answers
190
views
Is the speed of light universal for all mediums? [duplicate]
We know that the speed of light is constant in a vacuum and has the value c= 3× 10^8 m/s.
But in a medium such as glass(refractive index=1.5) the speed of light is 2× 10^8 m/s. Now considering the ...
- 141
-1
votes
2
answers
619
views
Speed of light and wavelength
Does the speed of Electromagnetic wave depend on its wave length? For vacuum I'm aware that it's a constant $c=\frac{1}{\sqrt{\mu_o\epsilon_o}}$. Similarly can we say speed of light in any medium is a ...
- 1,161