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Lenz's law states that the direction of the electric current induced in a conductor by a changing magnetic field is such that the magnetic field created by the induced current opposes changes in the initial magnetic field. It is named after physicist Heinrich Lenz, who formulated it in 1834. [1]
By Lenz's law, an eddy current creates a magnetic field that opposes the change in the magnetic field that created it, and thus eddy currents react back on the source of the magnetic field. For example, a nearby conductive surface will exert a drag force on a moving magnet that opposes its motion, due to eddy currents induced in the surface by ...
Mechanical work is necessary to drive this current. When the generated current flows through the conducting rim, a magnetic field is generated by this current through Ampère's circuital law (labelled "induced B" in the figure). The rim thus becomes an electromagnet that resists rotation of the disc (an example of Lenz's law). On the far side ...
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).
This is stated by Lenz's law, and the voltage is called back EMF. Inductance is defined as the ratio of the induced voltage to the rate of change of current causing it. [ 1 ] It is a proportionality constant that depends on the geometry of circuit conductors (e.g., cross-section area and length) and the magnetic permeability of the conductor ...
Coulomb's law can be found from Gauss's law (electrostatic form) and the Biot–Savart law can be deduced from Ampere's law (magnetostatic form). Lenz's law and Faraday's law can be incorporated into the Maxwell–Faraday equation. Nonetheless they are still very effective for simple calculations. Lenz's law; Coulomb's law; Biot–Savart law ...
Heinrich Friedrich Emil Lenz (German: [ˈeːmɪl ˈlɛnts]; also Emil Khristianovich Lenz; Russian: Эми́лий Христиа́нович Ленц; 12 February 1804 – 10 February 1865), usually cited as Emil Lenz [1] [2] or Heinrich Lenz in some countries, was a Russian physicist who is most noted for formulating Lenz's law in electrodynamics in 1834.
The minus sign represents Lenz's Law, Φ B is the magnetic flux through the open surface Σ , ∂Σ is the boundary of the open surface Σ ; the surface, in general, may be in motion and deforming, and so is generally a function of time.