All Questions
Tagged with refraction speed-of-light
46
questions
89
votes
9
answers
15k
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What really causes light/photons to appear slower in media?
I know that if we solve the Maxwell equation, we will end up with the phase velocity of light being related to the permeability and the permittivity of the material. But this is not what I'm ...
- 2,452
85
votes
4
answers
40k
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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
11
votes
6
answers
15k
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Do photons have acceleration?
Photons travel at the fastest speed in our universe, the speed of light.
Do photons have acceleration?
- 1,037
52
votes
3
answers
21k
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How does light speed up after coming out of a glass slab?
As I learned today in school, my teacher told me that when light enters a glass slab it slows down due to the change in density and it speeds up as it goes out of the glass slab. This causes a lateral ...
- 841
41
votes
4
answers
191k
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Why does wavelength change as light enters a different medium?
When light waves enter a medium of higher refractive index than the previous, why is it that:
Its wavelength decreases?
The frequency of it has to stay the same?
- 4,607
16
votes
2
answers
2k
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What happens if light/particles exceeded the speed of light for a particular medium?
While the speed of light in vacuum is a universal constant ($c$), the speed at which light propagates in other materials/mediums may be less than $c$. This is obviously suggested by the fact that ...
- 1,187
11
votes
1
answer
1k
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If refraction slows down light, isn't it possible to hold light still?
I have a quick question about the refraction of light, and I'm sorry if it seems a bit simplistic or even stupid, but I'm still learning.
We know that when light passes through a denser medium, it ...
- 289
9
votes
2
answers
51k
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Why does the light travel slower in denser medium? [duplicate]
Wikipedia says that "in general, the refractive index of a glass increases with its density." And the refraction index of water vapor is less than ice, and even less than liquid water. Is there any ...
- 1,168
7
votes
6
answers
19k
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Does light loses its energy when it passes through denser medium?
I know it does not because it emerges out of denser medium at 300,000 KM per second, but according to $E=mc^2$ and given that speed of light decreases inside denser medium with refractive index ...
- 181
7
votes
3
answers
6k
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How can a particle in a medium ever travel faster than light? [duplicate]
In some media, mass-carrying particles can go faster than light:
Cherenkov radiation, ... is electromagnetic radiation emitted when a charged particle... passes through a dielectric medium at a ...
- 657
2
votes
1
answer
5k
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Correlation between the refractive index and the density
The $v$ propagation speed of light in a transparent medium is related to the $c$ speed of light in vacuum through the relationship,
$$\boxed{n=c/v}$$
The constant $n$ is a pure number called ...
- 2,547
2
votes
2
answers
2k
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What do physicists mean when they say "speed of light"?
Does it make sense to say, "The speed of light varies?" Some may say right off the bat "Yes, it changes as a wave passes through a different medium." However, I'd like to say no, because when I hear ...
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63
votes
3
answers
4k
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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
41
votes
5
answers
13k
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Is light actually faster than what our present measurements tell us?
It is well established that the light speed in a perfect vacuum is roughly $3\times 10^8 \:\rm m/s$. But it is also known that outer space is not a perfect vacuum, but a hard vacuum. So, is the speed ...
user182521
21
votes
5
answers
4k
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Is the speed of light in all media independent of reference frame?
We know that, the speed of light in vacuum is independent of reference frame. I read the reason for this fact from Why and how is the speed of light in vacuum constant, i.e., independent of reference ...
- 5,306