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binis
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Refractive index is a function of velocity in the medium. How is this related to deviation angle inside the medium? I am not asking for the known formula, but for the mechanism behind it.
Of course I did. Should I had asked it in Quandum physics section?BvU said:Did you google anything at all? E.g. Snell's law?
So you found the relationship that your post is asking for !binis said:Of course I did
So what's wrong with the explanation on Wikipedia, for example?binis said:Of course I did.
Snell's law is a rule, not explanationBvU said:So you found the relationship that your post is asking for !
Do you mean the Fermat's principle?Ibix said:So what's wrong with the explanation on Wikipedia, for example?
I see. And the derivation (from Fermat principle) is not understood, not acceptable, something else ?binis said:Snell's law is a rule, not explanation
Many issues arise. 1. Since wave is spreading according to Huygens law in wavefronts, how it reaches the interface between the materials at an angle? The figure shows an arbitrarily cuted section of wavefronts to create a "light ray". 2. Interface in microscale is not flat but consists of distant molecules or atoms (see Bragg's law). 3. How is the interference resultant wave neither reinforced or canceled? 4. How is the resultant wave not Compton shifted? 5. Oscillation is an assumption inconsistent with electronic cloud. And what about opaque materials? By this explanation must be also transparent. 6. There must be a little loss of energy because the wave is totally absorbed by the glass (or quartz or liquid) at last, if medium's width is quite long (Lambert's law).Ibix said:What don't you understand about its explanation?
Because it's a plane wave, probably with a Gaussian intensity profile. Apply Huygens' principle to a plane wave in free space and you'll get a plane wave out.binis said:. 1. Since wave is spreading according to Huygens law in wavefronts, how it reaches the interface between the materials at an angle? The figure shows an arbitrarily cuted section of wavefronts to create a "light ray".
Bragg's law isn't relevant here - the wavelength of light is far too long. Scratches and imperfections on the surface on the 0.1##\mu##m scale will cause diffraction.binis said:2. Interface in microscale is not flat but consists of distant molecules or atoms (see Bragg's law).
Don't understand what you are asking.binis said:3. How is the interference resultant wave neither reinforced or canceled?
I don't think there are any nearly free electrons in glass. And even if there are have you worked out the Compton shift and compared it to the wavelength of light? Would you be able to see it?binis said:4. How is the resultant wave not Compton shifted?
No idea what you mean here.binis said:5. Oscillation is an assumption inconsistent with electronic cloud. And what about opaque materials? By this explanation must be also transparent.
Yes. There's also usually some reflection at the surface. So what?binis said:6. There must be a little loss of energy because the wave is totally absorbed by the glass (or quartz or liquid) at last, if medium's width is quite long (Lambert's law).
It has an explanation for the slowing down. It has an explanation for the divergence. But it doesn't explain how is Snell's law deduced from the slowing down.Ibix said:I must clarify my OP question: How is Snell's law formula mathematically deduced from the change in phase velocity?Ibix said:BvU said:Perhaps you can be a bit more specific:
Ibix said:The Wikipedia page on refraction does not mention Fermat's principle.
Ibix said:"may have wave packets that pass an observer at a slower rate" This is an arbitrary assumption. Is this observed elsewhere, in a TV antenna for example?Ibix said:What don't you understand about its explanation?
Energy decrease means frequency decrease.Ibix said:Yes. There's also usually some reflection at the surface. So what?
It explicitly does so in the second paragraph of the section headed Explanation for bending of light as it enters and exits a medium. What didn't you understand about it?binis said:It has an explanation for the slowing down. It has an explanation for the divergence. But it doesn't explain how is Snell's law deduced from the slowing down.
No. In wave optics energy decrease means amplitude decrease, and amplitude is not related to frequency. If you are thinking of the ##E=h\nu## relation from quantum mechanics, remember that it is the energy of a single photon. The beam is made up of many photons, so can lose energy without changing frequency as individual photons are absorbed.binis said:Energy decrease means frequency decrease.
Oscillation of the free electrons (i.g. inside a TV antenna) is known. Oscillation of the orbital electrons inside a material is unknown to me (not aware of QM).Ibix said:No idea what you mean here.
It’s hard to discuss matters involving QM if you don’t know some details. Read around about it. There’s plenty of good material out there.binis said:Oscillation of the free electrons (i.g. inside a TV antenna) is known. Oscillation of the orbital electrons inside a material is unknown to me (not aware of QM).
"the resulting "combined" wave may have wave packets that pass an observer at a slower rate."Ibix said:What didn't you understand about it?
You are misquoting, by accident I must presumebinis said:"the resulting "combined" wave may have wave packets that pass an observer at a slower rate."
This is an assumption. Is this observed elsewhere, in a TV antenna for example?
(emphasis mine)Wiki said:The resulting "combined" wave has wave packets that pass an observer at a slower rate.
Search for "wave packet" in the page. You are quoting from the first instance, binis from the second.BvU said:You are misquoting, by accident I must presume
No it's not, it's a statement of fact about combining two arbitrary waves. The combination may propagate slower, but the obvious counter example is combining two waves with the same frequency and propagation speed, which produces nothing more than a phase offset. But you aren't combining arbitrary waves, you are combining a light wave and the radiation from electrons driven by the wave. The result of that particular combination is a wave that travels slower.binis said:This is an assumption.
It is known as the fluorescent effect, having a different result.binis said:Oscillation of the orbital electrons inside a material is unknown to me (not aware of QM).
Phase velocity is the speed at which a wave travels through a medium. It is the rate at which the phase of the wave (represented by the peaks and troughs) moves through space.
Phase velocity is typically measured by dividing the wavelength of the wave by the period of the wave. This gives the distance the wave travels in one period, which is the phase velocity.
The relationship between phase velocity and deflection angle is that as the phase velocity increases, the deflection angle also increases. This means that the wave will travel through a medium at a faster speed, resulting in a larger deflection angle.
The phase velocity and deflection angle of a wave are affected by the properties of the medium it travels through. For example, the density and elasticity of the medium can impact the speed at which the wave travels and the angle at which it is deflected.
Yes, the phase velocity and deflection angle can be manipulated by changing the properties of the medium or by using external forces such as electric or magnetic fields. This can be useful in various applications, such as in telecommunications and medical imaging.