SIEMENS

unit of electrical conductance, symbolized S. In the case of direct current, the conductance in siemens is the reciprocal of the resistance in ohms (S = amperes/volts); in the case of alternating current, it is the reciprocal of the impedance in ohms. A former term for the reciprocal of the ohm is the mho (ohm spelled backward). It is disputed whether the siemens was named after the German-born engineer-inventor Sir William Siemens (182383) or his brother, the electrical engineer Werner von Siemens (181692).