
#1
Feb513, 04:25 PM

P: 31

I was thinking about refraction and phase velocity change, when i thought about whether the c in e=hc/lambda is always 3x10^8 or does it refer to the speed in the medium?
Thanks 



#2
Feb513, 06:00 PM

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PF Gold
P: 11,070

in ##E=hc/\lambda## ##c## is always the speed of light in vacuum.
if the speed in the medium is important, it will show up in equations as a refractive index. as far as the photon is concerned, the "medium" is an array of atoms with empty space in between. 



#3
Feb613, 01:24 AM

P: 31

So if wavelength decreases in a refractive medium, does that mean energy increases???




#4
Feb613, 04:30 AM

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PF Gold
P: 11,070

E=hc/lambda... C
No. The relationship in question is the QM one for individual photons.
The EM wave description carries energy differently. http://farside.ph.utexas.edu/teachin...s/node119.html ... it's a different model. 



#5
Feb613, 07:46 AM

P: 1,909

Anyway, you should have the formula getting back to E=hf which is valid in vacuum and media as well. 



#6
Feb613, 04:46 PM

P: 31

Cheers folks. I now see that the qm and wave models must be evaluated differently and that E=hf is a more useful formula to employ :).



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