quantitykind:ElectromotiveForce
In physics, electromotive force, or most commonly $emf$ (seldom capitalized), or (occasionally) electromotance is that which tends to cause current (actual electrons and ions) to flow. More formally, $emf$ is the external work expended per unit of charge to produce an electric potential difference across two open-circuited terminals. "Electromotive Force" is deprecated in the ISO System of Quantities.