The usual expression of the electrical conductivity is e^2*n_e/(m_e*v_ei) where e is the electrical charge, n_e the electron density, m_e electron mass, v_ei is collision frequency between electron-ion.
I believe this expression is written in CGS unit (ex: charge is in unit of statC or Fr) for convenient derivation and its dimensional check shows 1/s as described in Wikipedia. http://en.wikipedia.org/wiki/Electrical_resistivity_and_conductivity
But Wikipedia also mentioned that conductivity is expressed in S/m where S stands for Siemens in SI unit. S is SI derived unit and consisted of several SI basic units. Unfortunately I've actually failed to convert the conductivity from 1/s (CGS) to S/m (SI).
I originally thought it should be simple job but right now I can't go further.
There must be something simple I've missed. Could you help me to figure out what step I was wrong?
Using the same names:
e*n_e*v_ei=I, if you use SI (meters,coulombs and seconds, then you obtain amps)
You have also that S=I/V
V*e=0.5*m_e*v^2, where v is the electron speed in m/s, e=charge in coulombs and V is volts
I hope it helps
Thanks for reply!
It appears that the expression is at least the same in both SI and CGS, surprisingly. If parameters are treated as being written in CGS unit, expression has dimension of 1/s (second^(-1)) while is S/m if SI is used. Both are correct.
Could I add one more important question?
Is there any direct way to convert 1/s (CGS) to S/m (SI)?
I means s (second) is the common unit in both unit systems, thus we may be able to start with s to directly transform between unit systems. I think this make sense.
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