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

[vaatmoly]

Just above equation (30), it says "2πf_n=2nπ/L". Should it be "2πf_n=2nc'π/L" instead?

 

[Philip Koeck]

Just above equation (30), it says "2πf_n=2nπ/L". Should it be "2πf_n=2nc'π/L" instead?

Is f_n 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.

 

[vaatmoly]

You have to get the book and read it. It's part of the derivation of Johnson noise. The derivation is several pages long.

 

[Philip Koeck]

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?

 

[vaatmoly]

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 "2πf_n=2nπ/L" where L is the transmission line length, c' is the propagation velocity on the line, n is the mode number

 

[Philip Koeck]

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 "2πf_n=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.