# Electromagnetic induction

**inductionmagnetic inductioninducedinduceinductiveinducesinduced currentFaraday's Law of Inductioninduced magnetic fieldinducing**

Electromagnetic or magnetic induction is the production of an electromotive force (i.e., voltage) across an electrical conductor in a changing magnetic field.wikipedia

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### Electromotive force

**EMFelectromotive force (EMF)ℰ**

Electromagnetic or magnetic induction is the production of an electromotive force (i.e., voltage) across an electrical conductor in a changing magnetic field.

In electromagnetic induction, emf can be defined around a closed loop of conductor as the electromagnetic work that would be done on an electric charge (an electron in this instance) if it travels once around the loop.

### Michael Faraday

**FaradayFaraday, MichaelM. Faraday**

Michael Faraday is generally credited with the discovery of induction in 1831, and James Clerk Maxwell mathematically described it as Faraday's law of induction.

His main discoveries include the principles underlying electromagnetic induction, diamagnetism and electrolysis.

### Faraday's law of induction

**Faraday's lawMaxwell–Faraday equationelectromagnetic induction**

Michael Faraday is generally credited with the discovery of induction in 1831, and James Clerk Maxwell mathematically described it as Faraday's law of induction.

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 called electromagnetic induction.

### Maxwell's equations

**Maxwell equationsMaxwell equationMaxwell’s equations**

Faraday's law was later generalized to become the Maxwell–Faraday equation, one of the four Maxwell equations in his theory of electromagnetism.

This aspect of electromagnetic induction is the operating principle behind many electric generators: for example, a rotating bar magnet creates a changing magnetic field, which in turn generates an electric field in a nearby wire.

### Electromagnetism

**electromagneticelectrodynamicselectromagnetic force**

Faraday's law was later generalized to become the Maxwell–Faraday equation, one of the four Maxwell equations in his theory of electromagnetism.

In Faraday's law, magnetic fields are associated with electromagnetic induction and magnetism, and Maxwell's equations describe how electric and magnetic fields are generated and altered by each other and by charges and currents.

### James Clerk Maxwell

**MaxwellJ. C. MaxwellJames Maxwell**

Michael Faraday is generally credited with the discovery of induction in 1831, and James Clerk Maxwell mathematically described it as Faraday's law of induction.

In it he provided a conceptual model for electromagnetic induction, consisting of tiny spinning cells of magnetic flux.

### Electric motor

**motorelectric motorsmotors**

Electromagnetic induction has found many applications, including electrical components such as inductors and transformers, and devices such as electric motors and generators.

These are usually powered by electromagnetic induction.

### Transformer

**power transformerelectrical transformerprimary winding**

Electromagnetic induction has found many applications, including electrical components such as inductors and transformers, and devices such as electric motors and generators.

Electromagnetic induction, the principle of the operation of the transformer, was discovered independently by Michael Faraday in 1831, Joseph Henry in 1832, and others.

### Inductor

**inductorscoilinductive**

Electromagnetic induction has found many applications, including electrical components such as inductors and transformers, and devices such as electric motors and generators.

### Eddy current brake

**eddy current brakingEddy-current brakeeddy brakes**

However, unlike friction brakes, in which the drag force that stops the moving object is provided by friction between two surfaces pressed together, the drag force in an eddy current brake is an electromagnetic force between a magnet and a nearby conductive object in relative motion, due to eddy currents induced in the conductor through electromagnetic induction.

### Lorentz force

**magnetic forceLorentz force lawLorentz**

Faraday's law describes two different phenomena: the motional EMF generated by a magnetic force on a moving wire (see Lorentz force), and the transformer EMF this is generated by an electric force due to a changing magnetic field (due to the differential form of the Maxwell–Faraday equation).

The electric field in question is created by the changing magnetic field, resulting in an induced EMF, as described by the Maxwell–Faraday equation (one of the four modern Maxwell's equations).

### Electric generator

**generatorgeneratorselectrical generator**

Alternating current generating systems were known in simple forms from Michael Faraday's original discovery of the magnetic induction of electric current.

### Joseph Henry

**Henry, JosephHenryJoseph Henry Papers Project**

It was discovered independently by Joseph Henry in 1832.

### Faraday paradox

**inapplicability of Faraday's lawUse of special techniques with Faraday's law**

### Alternator

**turbo-alternatoralternatorsgenerator**

Alternating current generating systems were known in simple forms from the discovery of the magnetic induction of electric current in the 1830s.

### Inductance

**mutual inductanceinductivemutual induction**

From Faraday's law of induction, any change in magnetic field through a circuit induces an electromotive force (EMF) (voltage) in the conductors; this is known as electromagnetic induction.

### Homopolar generator

**Faraday diskFaraday Wheeldisc of copper**

A different implementation of this idea is the Faraday's disc, shown in simplified form on the right.

This machine can be analysed using Faraday's own law of electromagnetic induction.

### Magnetic core

**core lossiron coresoft iron**

If the core is electrically conductive, the changing magnetic field induces circulating loops of current in it, called eddy currents, due to electromagnetic induction.

### Electrical conductor

**conductorconductiveconductors**

Electromagnetic or magnetic induction is the production of an electromotive force (i.e., voltage) across an electrical conductor in a changing magnetic field.

### Lenz's law

**his important lawlawLenz effect**

Lenz's law describes the direction of the induced field.

### Torus

**toroidaltoriflat torus**

In Faraday's first experimental demonstration (August 29, 1831), he wrapped two wires around opposite sides of an iron ring or "torus" (an arrangement similar to a modern toroidal transformer).

### Galvanometer

**D'Arsonval galvanometertangent galvanometernull detector**

He plugged one wire into a galvanometer, and watched it as he connected the other wire to a battery.

### Magnetic flux

**fluxfluxes definition of flux used in electromagnetism**

This induction was due to the change in magnetic flux that occurred when the battery was connected and disconnected.

### Direct current

**DCdirect-currentDC current**

For example, he saw transient currents when he quickly slid a bar magnet in and out of a coil of wires, and he generated a steady (DC) current by rotating a copper disk near the bar magnet with a sliding electrical lead ("Faraday's disk").

### Line of force

**lines of forcelines**

Faraday explained electromagnetic induction using a concept he called lines of force.