Two questions about light and sound

[stester77s]

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1. Why does light travel more slowly in an optically dense medium (n>1)?
- I understand that this is because the atoms of the optically dense medium are constantly absorbing and then releasing the light. But could someone with a deeper understanding of the theory behind this explain this phenomenon (such as, why and how does this slow it down just because it's being absorbed and submitted - that's not instantaneous? Why is the light not completely dispersed and travel in random directions since it's constantly being absorbed and emitted? etc.)

2. Does light and sound (and other forms of waves) lose amplitude as it travels?
-How does this happen, and why?

 

[DrknoSDN]

2. EM waves don't lose amplitude when propagating through a vacuum while physical waves are dependent on the movement of molecules and lose energy to heat and friction at the molecular level.

1. It is not instantaneous, remember that there is a small time delay between when an electron gets excited to a high energy orbital and when it returns to its previous low energy state.
Light does disperse (not in vacuo), however the space between molecules compared to the relative size of the actual atomic components is drastically different. Even an optically dense medium is mostly empty space from the perspective of light.

 

[stester77s]

2. EM waves don't lose amplitude when propagating through a vacuum while physical waves are dependent on the movement of molecules and lose energy to heat and friction at the molecular level.

1. It is not instantaneous, remember that there is a small time delay between when an electron gets excited to a high energy orbital and when it returns to its previous low energy state.
Light does disperse (not in vacuo), however the space between molecules compared to the relative size of the actual atomic components is drastically different. Even an optically dense medium is mostly empty space from the perspective of light.

Thank you! as for #2 - Do EM waves lose amplitude when propagating through a dense medium (n>>1)?

If so, how does this occur?

Also, an electron in it's ground state can absorb a photon - raise to a certain energy level, fall back down to the ground level - and then release a photon of the same exact energy as the one that it originally absorbed. Correct?

 

[DrknoSDN]

I believe that EM waves can lose energy because light can heat up the medium it's traveling through. However I don't know enough about the quantum mechanics properties to say that the "amplitude" is changing or that EM waves have amplitude at all. The only reason I say they don't lose amplitude in a vacuum is because the electric and magnetic fields are always perpendicular to one another allowing the loss-less self propagation of the photon.

Energy of a photon is related to hv/lambda. That is the reason why snells law describes the bending of light. Planks constant and frequency must remain the same so if the energy of the photons do not change drastically, then the wavelength shortens by a factor of n when entering an optically dense medium.
If you are talking about the transfer of energy from light to heat or something I believe the frequency changes, but I don't know how make a comparison to "amplitude". Light does have intensity but I believe that is a different property that follows inverse square rules. I don't belive quantum mechanics allows you to say that a single photon has an amplitude, only that you can have a probability curve associated with an intensity of light (many photons), if that makes any sense. =/
> This < post references intensity of light/constructive interference