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For a circuit using a battery source, the emf is due solely to the chemical forces in the battery. For a circuit using an electric generator, the emf is due solely to a time-varying magnetic forces within the generator. Both a 1 volt emf and a 1 volt potential difference correspond to 1 joule per coulomb of charge.
Faraday's law of induction (or simply Faraday's law) is a law of electromagnetism predicting how a magnetic field will interact with an electric circuit to produce an electromotive force (emf). This phenomenon, known as electromagnetic induction , is the fundamental operating principle of transformers , inductors , and many types of electric ...
The emf generated by Faraday's law of induction due to relative movement of a circuit and a magnetic field is the phenomenon underlying electrical generators. When a permanent magnet is moved relative to a conductor, or vice versa, an electromotive force is created.
That is, the back-EMF is also due to inductance and Faraday's law, but occurs even when the motor current is not changing, and arises from the geometric considerations of an armature spinning in a magnetic field. This voltage is in series with and opposes the original applied voltage and is called "back-electromotive force" (by Lenz's law).
The magnetic field strength depends on the magnitude of the electric current, and therefore follows any changes in the magnitude of the current. From Faraday's law of induction, any change in magnetic field through a circuit induces an electromotive force (EMF) in the conductors, a process known as electromagnetic induction. This induced ...
Maxwell's equations on a plaque on his statue in Edinburgh. Maxwell's equations, or Maxwell–Heaviside equations, are a set of coupled partial differential equations that, together with the Lorentz force law, form the foundation of classical electromagnetism, classical optics, electric and magnetic circuits.
The induced electromotive force in any closed circuit is equal to the negative of the time rate of change of the magnetic flux enclosed by the circuit. [2] [3] This version of Faraday's law strictly holds only when the closed circuit is a loop of infinitely thin wire, [4] and is invalid in other circumstances. It ignores the fact that Faraday's ...
Load resistance of circuit R ext = Ω = V A −1 = J s C −2 [M][L] 2 [T] −3 [I] −2: Electromotive force (emf), voltage across entire circuit including power supply, external components and conductors E