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. (http://qudt.org/schema/qudt/LatexString)