Devices that can provide emf include electrochemical cells, thermoelectric devices, solar cells, photodiodes, electrical generators, inductors, transformers and even Van de Graaff generators. In nature, emf is generated … See more

Electromotive force is often denoted by or ℰ.
In a device without internal resistance, if an electric charge passing through that device gains an energy via work, the net emf for that device is the energy gained per unit charge See more

When multiplied by an amount of charge the emf yields a thermodynamic work term that is used in the formalism for the change in See more

Chemical sources
The question of how batteries (galvanic cells) generate an emf occupied scientists for most of the 19th century. The "seat of the electromotive … See more

In 1801, Alessandro Volta introduced the term "force motrice électrique" to describe the active agent of a battery (which he had invented around 1798). This is called the "electromotive force" in English.
Around 1830, Michael Faraday established that chemical … See more

Inside a source of emf (such as a battery) that is open-circuited, a charge separation occurs between the negative terminal N and the positive … See more

Although an electrical potential difference (voltage) is sometimes called an emf, however they are formally distinct concepts:
• Emf is the cause of a potential difference. Potential difference in turn is a cause of current flow. See more