# Lenz's law

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Related to Lenz's law: Faraday's law, Right hand rule

## Lenz's law,

physical law, discovered by the German scientist H. F. E. Lenz in 1834, that states that the electromotive forceelectromotive force,
abbr. emf, difference in electric potential, or voltage, between the terminals of a source of electricity, e.g., a battery from which no current is being drawn. When current is drawn, the potential difference drops below the emf value.
(emf) induced in a conductor moving perpendicular to a magnetic field tends to oppose that motion. When an electric motormotor, electric,
machine that converts electrical energy into mechanical energy. When an electric current is passed through a wire loop that is in a magnetic field, the loop will rotate and the rotating motion is transmitted to a shaft, providing useful mechanical work.
is in operation, the armature is turning in a magnetic field, and an emf is thus induced in it. Lenz's law requires that this emf, called back emf or counter emf, oppose the motion of the armature and also the original emf, causing the motor to operate. As a result, the speed of the motor changes in such a way that the energy supplied by the original voltage source less the energy required to overcome the back emf is always exactly equal to the sum of the energy used to drive the mechanism to which the motor is attached and the energy lost as heat within the motor. Lenz's law may thus be seen as a consequence of the law of conservation of energy (see conservation lawsconservation laws,
in physics, basic laws that together determine which processes can or cannot occur in nature; each law maintains that the total value of the quantity governed by that law, e.g., mass or energy, remains unchanged during physical processes.
, in physics).

## Lenz's law

A law of electromagnetism which states that, whenever there is an induced electromotive force (emf) in a conductor, it is always in such a direction that the current it would produce would oppose the change which causes the induced emf. If the change is the motion of a conductor through a magnetic field, the induced current must be in such a direction as to produce a force opposing the motion. If the change causing the emf is a change of flux threading a coil, the induced current must produce a flux in such a direction as to oppose the change. Lenz's law is a form of the law of conservation of energy, since it states that a change cannot propagate itself. See Conservation of energy, Electromagnetic induction

## Lenz’s Law

a law on the direction of induced currents, that is, currents arising as a result of electromagnetic induction. Lenz’s law is a consequence of the law of the conservation of energy.

Formulated in 1833 by H. F. E. Lenz, the law states that an induced current arising in a closed circuit is so directed that the magnetic induction flux created by the current and passing through the circuit tends to oppose the change in flux that causes the given current. Thus, for example, the induced current in a loop placed in a magnetic field B, which is directed perpendicularly to the plane of the coil and away from the observer, will have a counterclockwise direction if the field increases with time and a clockwise direction if the field decreases with time.

## Lenz's law

[′lenz·əz ‚lȯ]
(electromagnetism)
The law that whenever there is an induced electromotive force (emf) in a conductor, it is always in such a direction that the current it would produce would oppose the change which causes the induced emf.
References in periodicals archive ?
By the time they had finished viewing the second section of the video--which correctly explained the theory behind the Meissner Effect--the students had been alerted to the nature of the Lenz's Law misconception.
The most highly-publicised piece (and the one with the biggest stand) was the Colmer-tech, which reverses Lenz's law of physics by use of a magnet, thus making it possible for a current to flow in opposition to the voltage - no physics lesson intended.

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