نظرة عامة. For an element conducting direct current, electrical resistance R and electrical conductance G are defined as G = ¹⁄ R = I ⁄ V 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 [S] = [Ω⁻¹] = [A/V] where Ω is the ohm, A is the ampere, and ...