Should Equation (30) be Revised to '2πfn=2nc'π/L'?

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The discussion centers on the equation "2πfn=2nπ/L" and whether it should be revised to "2πfn=2nc'π/L". Participants clarify that fn represents the frequency of photon modes in a transmission line, where L is the length of the line and c' is the propagation velocity. The consensus is that the second equation is dimensionally correct, as frequency has dimensions of 1/time, necessitating the inclusion of c' for dimensional accuracy. The context of this equation is tied to the derivation of Johnson noise, which requires a thorough understanding of the underlying principles.

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vaatmoly
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Just above equation (30), it says "2πfn=2nπ/L". Should it be "2πfn=2nc'π/L" instead?
 
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vaatmoly said:
Just above equation (30), it says "2πfn=2nπ/L". Should it be "2πfn=2nc'π/L" instead?
Is fn a spatial or a temporal frequency?
What is n and L?
Maybe you could make pdf of the section, so one can see the context.
 
You have to get the book and read it. It's part of the derivation of Johnson noise. The derivation is several pages long.
 
vaatmoly said:
You have to get the book and read it. It's part of the derivation of Johnson noise. The derivation is several pages long.
Maybe you could just define the quantities in the equation?
 
Yes, sure.
We are considering photon modes in a transmission line(an electromagnetic system in one dimension). The transmission line has 2 photon modes(one propagating in each direction) of frequency "2πfn=2nπ/L" where L is the transmission line length, c' is the propagation velocity on the line, n is the mode number
 
vaatmoly said:
Yes, sure.
We are considering photon modes in a transmission line(an electromagnetic system in one dimension). The transmission line has 2 photon modes(one propagating in each direction) of frequency "2πfn=2nπ/L" where L is the transmission line length, c' is the propagation velocity on the line, n is the mode number
Then it's pretty clear. The frequency has dimension 1/time so you need the c in the equation to get the dimensions right.
The 2nd equation could be right, the 1st can't be.
 

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