A unit measure of electrical conduction. The facility with which a substance conducts electricity, as represented by the current density per unit electrical-potential gradient in the direction of flow. Electrical conductivity is the reciprocal of electrical resistivity and is expressed in units such as mhos (reciprocal ohms) per cm. It is an intrinsic property of a given type of material under given physical conditions (dependent mostly on temperature). Conductance, on the other hand, varies with the dimensions of the conducting system and is the reciprocal of the electrical resistance.