Hello, Dan, Conductivity is defined differently in Millman and Halkias' Electronic Devices And Circuits. (Cf. 1967 edition, page 54.)
Equation 3-3: (sigma) equals (n) x (e) x (mu) where: n is the concentration of mobile charges, which are free electrons in metals in the Millman and Halkias' discussion, e is the magnitude of charge of the mobile charge, and mu is the mobility of the mobile charge. Millman and Halkias give the MKS unit of n as electrons per cubic meter, the MKS unit of e as coulombs per electron, the MKS unit of mu as square meters per volt-second, and "the conductivity (is)..in reciprocal ohm-meters". On the other hand, Johnson, Johnson, Hilburn and Scott's Electric Circuit Analysis (3rd edition, page 32) states conductance is the reciprocal of resistance, G= 1/R , and "the SI unit for conductance is the siemens, symbolized by S... thus 1 S = 1 A/V. Another unit of conductance, widely used in the United States, is the mho, which is ohm spelled backwards." Millman and Halkias, and Johnson, Johnson, Hilburn and Scott, went through many editions and were used and accepted by generations of EEs. They clearly meant distinct things by the two distinct words, conductivity and conductance. Best regards, Matthew
