[Wien] the unit of optical conductivity sigma!

[franco]

   The units of conductivity are either  1/(Ohm cm) or 1/s, which
are the same.  You can see this as follows (there may be more
elegant derivations, but this is first that I could think of).
Start by remembering the definitions in terms of units (neglect
numerical values):
  Ohm = Volt / Amp ;  Amp = Coul / s [Coul=Coulomb] ;  Volt Coul = Joule
hence
  Ohm = Volt s / Coul  = Joule s / Coul^2  [Coul^2 = Coul square]
Now what about Coulomb?  Remember that two unit charges q at distance
of 1 m produce the unit force of 1 Newton, hence 1 N = q^2/m^2 or
       q^2 = Coul**2 = N m^2 = kg m^3 /s^2 ,
and that Joule = N m = Kg m^2 / s^2.
It follows that
             Ohm = s / m   (or Ohm = s/cm if you prefer)
and therefore
   Ohm m = s   and  1/(Ohm m) = 1/s
   [or, forgetting numerical constants, 1/(Ohm cm)=1/s].

Franco Jona
















On Tue, 2007-07-31 at 15:52 +0000, 蔡 孟秋 wrote:
> Dear Peter , Stefaan and wien user:
> 
> When I calculated the optical properties with wien2k, I see the the the 
> unit of optical conductivity sigma in the file of case.absorp is [1 / (Ohm 
> cm)]. But the expression is 1/sec (1/s) in other references. What is it the 
> 
> relation between two.
> 
> Thank you  in advance!
> 
> Sincerely yours,
> 
> Meng-Qiu Cai
> 
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