# Larmor precession

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Larmor precession

In physics, Larmor precession (named after Joseph Larmor) refers to the precession of the magnetic moments of electrons, atomic nuclei, and atoms about an external magnetic field. The magnetic field exerts a torque on the magnetic moment,:$vec\left\{Gamma\right\} = vec\left\{mu\right\} imesvec\left\{B\right\}=gammavec\left\{J\right\} imesvec\left\{B\right\}$

where $vec\left\{Gamma\right\}$ is the torque, $vec\left\{J\right\}$ is the angular momentum vector, $vec\left\{B\right\}$ is the external magnetic field, $imes$ is the cross product, and $gamma$ is the gyromagnetic ratio which gives the proportionality constant between the magnetic moment and the angular momentum. The angular momentum vector $vec\left\{J\right\}$ precesses about the external field axis with an angular frequency known as the Larmor frequency,:$omega = gamma B$ where "$omega$" is the angular frequency and "B" is the magnitude of the magnetic field.

A famous 1935 paper published by Lev Landau and Evgeny Lifshitz predicted the existence of ferromagnetic resonance of the Larmor precession, which was verified experimentally and independently by J. H. E. Griffiths (UK) and E. K. Zavoiskij (USSR) in 1946.

Larmor precession is important in nuclear magnetic resonance.

ee also

* Rabi cycle
* [http://hyperphysics.phy-astr.gsu.edu/hbase/nuclear/larmor.html Georgia State University HyperPhysics page on Larmor Frequency]

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• Larmor precession — Larmoro precesija statusas T sritis fizika atitikmenys: angl. Larmor precession vok. Larmorpräzession, f rus. ларморовская прецессия, f pranc. précession de Larmor, f …   Fizikos terminų žodynas

• larmor precession — noun Usage: usually capitalized L : the precession of a particle having magnetic moment (as an atom when spinning in a magnetic field) * * * /lahr mawr/, Physics. the precession of charged particles, as electrons, placed in a magnetic field, the… …   Useful english dictionary

• Larmor precession — /lahr mawr/, Physics. the precession of charged particles, as electrons, placed in a magnetic field, the frequency of the precession (Larmor frequency) being equal to the electronic charge times the strength of the magnetic field divided by 4 pi… …   Universalium

• Larmor precession — /lamə prəˈsɛʃən/ (say lahmuh pruh seshuhn) noun the precession of a charged particle in a magnetic field. {named after Sir Joseph Larmor, 1857–1947, English physicist} …   Australian English dictionary

• Larmor precession — noun The precession of the motion of charged particles, or particles having a magnetic moment, in a magnetic field …   Wiktionary

• Larmor precession frequency — Larmoro precesijos dažnis statusas T sritis fizika atitikmenys: angl. angular frequency of Larmor precession; Larmor frequency; Larmor precession frequency vok. Larmor Frequenz, f; Larmor Kreisfrequenz, f; Larmor Präzessionsfrequenz, f rus.… …   Fizikos terminų žodynas

• Larmor precession frequency — kampinis Larmoro dažnis statusas T sritis fizika atitikmenys: angl. Larmor angular frequency; Larmor frequency; Larmor precession frequency vok. Larmor Kreisfrequenz, f rus. круговая частота Лармора, f; угловая частота Лармора, f pranc. fréquence …   Fizikos terminų žodynas

• Larmor precession frequency — kampinis Larmoro dažnis statusas T sritis Standartizacija ir metrologija apibrėžtis Apibrėžtį žr. priede. priedas( ai) Grafinis formatas atitikmenys: angl. Larmor angular frequency; Larmor precession frequency vok. Larmor Kreisfrequenz, f rus.… …   Penkiakalbis aiškinamasis metrologijos terminų žodynas

• angular frequency of Larmor precession — Larmoro precesijos dažnis statusas T sritis fizika atitikmenys: angl. angular frequency of Larmor precession; Larmor frequency; Larmor precession frequency vok. Larmor Frequenz, f; Larmor Kreisfrequenz, f; Larmor Präzessionsfrequenz, f rus.… …   Fizikos terminų žodynas

• Precession — Précession Précession d un gyroscope La précession est le nom donné au changement graduel d orientation de l axe de rotation d un objet ou, de façon plus générale, d un vecteur sous l action de l environnement, par exemple, quand un couple lui… …   Wikipédia en Français