Linked Questions

11
votes
3answers
2k views

Do photons actually slow down in a medium, or is the speed decrease just apparent? [duplicate]

Some places I've read flat out say light actually slows down in a medium, some say the speed decresae is just apparent but not real and that the photons still travel at the constant speed of light. I'...
8
votes
2answers
38k views

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 ...
4
votes
5answers
2k views

Why is the speed of light said to be constant when we know it slows down in a medium? [duplicate]

If we ask someone what the speed of light is, they will say that it is constant and its value is $3\times 10^{8}\ \mathrm{m/s}$. But if we recall refraction of light, we say that when the light ...
1
vote
1answer
12k views

What causes refraction of visible light? [duplicate]

Refraction is the bending of a wave when it enters a medium where its speed is different. The refraction of light when it passes from a fast medium to a slow medium bends the light ray toward the ...
-1
votes
1answer
1k views

Does the speed of light vary depending on what it travels through? [duplicate]

The title is pretty much self explanatory. Does the speed of light vary depending on what it is traveling through? The speed of light through vacuum is 299792458 meters per second but does it change ...
0
votes
1answer
949 views

What causes refraction of light? [duplicate]

Time and again, I've been told that the change in the velocity of light makes it bend at the interface between two different media. But is there any explanation as to why that change occurs? Or is it ...
0
votes
1answer
496 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
votes
1answer
396 views

Does light really slow down when moving through a transparent medium? [duplicate]

I assume its speed doesn't change but the photons get absorbed and destructed by the materials' atoms and then they emit new photons. Is that true?
0
votes
0answers
238 views

What happens to light as it passes through a medium? [duplicate]

Light travels at its maximum speed in a vacuum. But when it enters a medium such as glass, air, water, etc. it slows down. What is actually happening to the photons as they pass through the medium? ...
0
votes
1answer
172 views

Is the speed of photon always $c_0$? [duplicate]

The propagation of light in medium is sometimes interpreted as the photons moving with $c_0$ (the speed of light in vacuum), occasionally absorbed by particles and released again by transition, ...
1
vote
1answer
99 views

Do the mediums decrease or increase the speed of light? (source to target) [duplicate]

If sun is the source of light then is it possible that the speed of light might increase depending on the mediums its going through or its not possible.
-1
votes
1answer
101 views

Change in Speed of Light [duplicate]

Whenever light enters from air to glass its speed decreases but when it cross the glass and again come in air its speed increases. What is the reason behind this property? What is slowing it and what ...
1
vote
1answer
76 views

Constancy of the Speed of Light in a medium [duplicate]

I've read both that the speed of light must remain constant and that light is slowed down the greater the index of refraction. So does the speed of light actually get slower or does space-time warp to ...
0
votes
0answers
22 views

Can measuring the refraction index in an object measure the strength of the quantum gravity between atoms of the object? [duplicate]

Is measuring the refraction index of an object a way of measuring the strength of the gravitational force between the atoms of the object (measuring quantum gravity)? From reading Snell's law of ...
72
votes
7answers
10k views

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 ...

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