Siemens (unit) plural. For a conducting element, electrical resistance "R" and electrical conductance "G" are defined as where "I" is the electric current through the object and "V" is the voltage (electrical potential difference) across the object. The unit siemens for the conductance "G" is defined by where Ω is the ohm, A is the ampere, and V is the volt. For a device with a conductance of one siemens, the electric current through the device will increase by one ampere for every increase of one volt of electric potential difference across the device. The conductance of a resistor with a resistance
Ohm 1881 the "Congrès internationale des électriciens" (international conference of electricians) defined a "practical" unit of Ohm for the resistance, based on CGS units, using a mercury column 1 sq. mm. in cross-section, approximately 104.9 cm in length at 0 °C, similar to the apparatus suggested by Siemens. A "legal" ohm, a reproducible standard, was defined by the international conference of electricians at Paris in 1884 as the resistance of a mercury column of specified weight and 106 cm long; this was a compromise value between the B. A. unit (equivalent to 104.7 cm), the Siemens unit (100 cm by definition),