# Faraday's law of induction

**Faraday's lawMaxwell–Faraday equationelectromagnetic inductionFaradayinducesinductionMaxwell-Faraday equationelctromagnetic inductionFaraday inductionFaraday's induction law**

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.wikipedia

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### Transformer

**power transformerelectrical transformerprimary winding**

It is the fundamental operating principle of transformers, inductors, and many types of electrical motors, generators and solenoids.

Faraday's law of induction discovered in 1831 described the induced voltage effect in any coil due to changing magnetic flux encircled by the coil.

### Electromagnetic induction

**inductionmagnetic inductioninduced**

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.

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.

### Inductor

**inductorscoilinductive**

It is the fundamental operating principle of transformers, inductors, and many types of electrical motors, generators and solenoids.

When the current flowing through an inductor changes, the time-varying magnetic field induces an electromotive force (e.m.f.) (voltage) in the conductor, described by Faraday's law of induction.

### Magnetic field

**magnetic fieldsmagneticmagnetic flux density**

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.

He described this phenomenon in what is known as Faraday's law of induction.

### Electromotive force

**EMFelectromotive force (EMF)ℰ**

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.

The general principle governing the emf in such electrical machines is Faraday's law of induction.

### Maxwell's equations

**Maxwell equationsMaxwell equationMaxwell’s equations**

The Maxwell–Faraday equation (listed as one of Maxwell's equations) describes the fact that a spatially varying (and also possibly time-varying, depending on how a magnetic field varies in time) electric field always accompanies a time-varying magnetic field, while Faraday's law states that there is EMF (electromotive force, defined as electromagnetic work done on a unit charge when it has traveled one round of a conductive loop) on the conductive loop when the magnetic flux through the surface enclosed by the loop varies in time.

The Maxwell–Faraday version of Faraday's law of induction describes how a time varying magnetic field creates ("induces") an electric field.

### Electric generator

**generatorgeneratorselectrical generator**

It is the fundamental operating principle of transformers, inductors, and many types of electrical motors, generators and solenoids.

The principle, later called Faraday's law, is that an electromotive force is generated in an electrical conductor which encircles a varying magnetic flux.

### Michael Faraday

**FaradayFaraday, MichaelM. Faraday**

Electromagnetic induction was discovered independently by Michael Faraday in 1831 and Joseph Henry in 1832. Michael Faraday explained electromagnetic induction using a concept he called lines of force.

His demonstrations established that a changing magnetic field produces an electric field; this relation was modelled mathematically by James Clerk Maxwell as Faraday's law, which subsequently became one of the four Maxwell equations, and which have in turn evolved into the generalization known today as field theory.

### Electricity

**electricalelectricelectrically**

Further analysis of this process, known as electromagnetic induction, enabled him to state the principle, now known as Faraday's law of induction, that the potential difference induced in a closed circuit is proportional to the rate of change of magnetic flux through the loop.

### Solenoid

**solenoidselectromechanical solenoidmagnetizing current loop**

The force applied to the armature is proportional to the change in inductance of the coil with respect to the change in position of the armature, and the current flowing through the coil (see Faraday's law of induction).

### Lenz's law

**his important lawlawLenz effect**

Lenz's law, formulated by Emil Lenz in 1834, describes "flux through the circuit", and gives the direction of the induced EMF and current resulting from electromagnetic induction (elaborated upon in the examples below).

Lenz's law is contained in the rigorous treatment of Faraday's law of induction, where it finds expression by the negative sign:

### 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.

The relationship is given by Faraday's law:

### Field line

**Electric field linesmagnetic flux linesfield lines**

. In more visual terms, the magnetic flux through the wire loop is proportional to the number of magnetic flux lines that pass through the loop.

They can also form closed loops, or extend to or from infinity, or continue forever without closing in on themselves.

### Lorentz force

**magnetic forceLorentz force lawLorentz**

The equation of Faraday's law can be derived by the Maxwell–Faraday equation (describing transformer EMF) and the Lorentz force (describing motional EMF).

Variations on this basic formula describe the magnetic force on a current-carrying wire (sometimes called Laplace force), the electromotive force in a wire loop moving through a magnetic field (an aspect of Faraday's law of induction), and the force on a charged particle which might be traveling near the speed of light (relativistic form of the Lorentz force).

### Electric field

**electricelectrostatic fieldelectrical field**

is the electric field and

Electric fields are caused by electric charges, described by Gauss's law, or varying magnetic fields, described by Faraday's law of induction.

### Curl (mathematics)

**curlcurl operatorcross product of a curl**

is the curl operator and again

### Poisson's equation

**Poisson equationPoissonPoisson problem**

-field can be expressed as the gradient of a scalar field that is a solution to Poisson's equation, and has a zero path integral.

In the absence of a changing magnetic field, B, Faraday's law of induction gives

### Electromagnetism

**electromagneticelectrodynamicselectromagnetic force**

### Electrical network

**circuitelectrical circuitelectric circuit**

### Electric motor

**motorelectric motorsmotors**

### Joseph Henry

**Henry, JosephHenryJoseph Henry Papers Project**

Electromagnetic induction was discovered independently by Michael Faraday in 1831 and Joseph Henry in 1832.

### Torus

**toroidaltoriflat torus**

In Faraday's first experimental demonstration of electromagnetic induction (August 29, 1831), he wrapped two wires around opposite sides of an iron ring (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.

### 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**

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