# Electromotive force    Electrical action produced by a non-electrical source, measured in volts.

- Electromotive force 147 related topics ## Transformer

Passive component that transfers electrical energy from one electrical circuit to another circuit, or multiple circuits.

Passive component that transfers electrical energy from one electrical circuit to another circuit, or multiple circuits.                           A varying current in any coil of the transformer produces a varying magnetic flux in the transformer's core, which induces a varying electromotive force across any other coils wound around the same core. ## Voltage

Difference in electric potential between two points, which is defined as the work needed per unit of charge to move a test charge between the two points.

Difference in electric potential between two points, which is defined as the work needed per unit of charge to move a test charge between the two points.     Electric potential differences between points can be caused by the build-up of electric charge (e.g., a capacitor), and from an electromotive force (e.g., electromagnetic induction in generator, inductors, and transformers). ## Thermoelectric effect

Direct conversion of temperature differences to electric voltage and vice versa via a thermocouple.

Direct conversion of temperature differences to electric voltage and vice versa via a thermocouple.  The Seebeck effect is a classic example of an electromotive force (EMF) and leads to measurable currents or voltages in the same way as any other EMF. ## Magnetic flux

Surface integral of the normal component of the magnetic field B over that surface.

Surface integral of the normal component of the magnetic field B over that surface.   For example, a change in the magnetic flux passing through a loop of conductive wire will cause an electromotive force, and therefore an electric current, in the loop. ## Electric generator

Device that converts motive power into electric power for use in an external circuit.

Device that converts motive power into electric power for use in an external circuit.            The principle, later called Faraday's law, is that an electromotive force is generated in an electrical conductor which encircles a varying magnetic flux.       Faraday's law of induction (briefly, Faraday's law) is a basic law of electromagnetism predicting how a magnetic field will interact with an electric circuit to produce an electromotive force (emf)—a phenomenon known as electromagnetic induction. ## Electric battery

Source of electric power consisting of one or more electrochemical cells with external connections for powering electrical devices.

Source of electric power consisting of one or more electrochemical cells with external connections for powering electrical devices.        Each half-cell has an electromotive force (emf, measured in volts) relative to a standard. ## Volt     The volt is the derived unit for electric potential, electric potential difference (voltage), and electromotive force. ## Alessandro Volta

Italian physicist, chemist and lay Catholic who was a pioneer of electricity and power who is credited as the inventor of the electric battery and the discoverer of methane.

Italian physicist, chemist and lay Catholic who was a pioneer of electricity and power who is credited as the inventor of the electric battery and the discoverer of methane.     In this way he discovered the electrochemical series, and the law that the electromotive force (emf) of a galvanic cell, consisting of a pair of metal electrodes separated by electrolyte, is the difference between their two electrode potentials (thus, two identical electrodes and a common electrolyte give zero net emf). ## Inductance

Tendency of an electrical conductor to oppose a change in the electric current flowing through it.

Tendency of an electrical conductor to oppose a change in the electric current flowing through it.  From Faraday's law of induction, any change in magnetic field through a circuit induces an electromotive force (EMF) (voltage) in the conductors, a process known as electromagnetic induction.

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