Lorentz force

the force on a charged particle moving through a region containing both electric and magnetic fields.[196065; named after H. A. LORENTZ]
* * *
▪ physicsthe force exerted on a charged particle q moving with velocity v through an electric E and magnetic field B. The entire electromagnetic force F on the charged particle is called the Lorentz force (after the Dutch physicist Hendrik A. Lorentz (Lorentz, Hendrik Antoon)) and is given byF = qE + qv × B.The first term is contributed by the electric field. The second term is the magnetic force and has a direction perpendicular to both the velocity and the magnetic field. The magnetic force is proportional to q and to the magnitude of the vector cross product v × B. In terms of the angle ϕ between v and B, the magnitude of the force equals qvB sin ϕ. An interesting result of the Lorentz force is the motion of a charged particle in a uniform magnetic field. If v is perpendicular to B (i.e., with the angle ϕ between v and B of 90°), the particle will follow a circular trajectory with a radius of r = mv/qB. If the angle ϕ is less than 90°, the particle orbit will be a helix with an axis parallel to the field lines. If ϕ is zero, there will be no magnetic force on the particle, which will continue to move undeflected along the field lines. Charged particle accelerators (particle accelerator) like cyclotrons (cyclotron) make use of the fact that particles move in a circular orbit when v and B are at right angles. For each revolution, a carefully timed electric field gives the particles additional kinetic energy, which makes them travel in increasingly larger orbits. When the particles have acquired the desired energy, they are extracted and used in a number of different ways, from fundamental studies of the properties of matter to the medical treatment of cancer.The magnetic force on a moving charge reveals the sign of the charge carriers in a conductor. A current flowing from right to left in a conductor can be the result of positive charge carriers moving from right to left or negative charges moving from left to right, or some combination of each. When a conductor is placed in a B field perpendicular to the current, the magnetic force on both types of charge carriers is in the same direction. This force gives rise to a small potential difference between the sides of the conductor. Known as the Hall effect, this phenomenon (discovered by the American physicist Edwin H. Hall (Hall, Edward)) results when an electric field is aligned with the direction of the magnetic force. The Hall effect shows that electrons dominate the conduction of electricity in copper. In zinc, however, conduction is dominated by the motion of positive charge carriers. Electrons in zinc that are excited from the valence (valence electron) band leave holes, which are vacancies (i.e., unfilled levels) that behave like positive charge carriers. The motion of these holes accounts for most of the conduction of electricity in zinc.If a wire with a current i is placed in an external magnetic field B, how will the force on the wire depend on the orientation of the wire? Since a current represents a movement of charges in the wire, the Lorentz force acts on the moving charges. Because these charges are bound to the conductor, the magnetic forces on the moving charges are transferred to the wire. The force on a small length dl of the wire depends on the orientation of the wire with respect to the field. The magnitude of the force is given by idlB sin ϕ, where ϕ is the angle between B and dl. There is no force when ϕ = 0 or 180°, both of which correspond to a current along a direction parallel to the field. The force is at a maximum when the current and field are perpendicular to each other. The force is given bydF= idl × B.Again, the vector cross product denotes a direction perpendicular to both dl and B.* * *
Universalium. 2010.
Look at other dictionaries:
Lorentz force — This article is about the equation governing the electromagnetic force. For a qualitative overview of the electromagnetic force, see Electromagnetism. For magnetic force of one magnet on another, see force between magnets. Electromagnetism … Wikipedia
Lorentz force — Lorenco jėga statusas T sritis Standartizacija ir metrologija apibrėžtis Jėga, kuria elektromagnetinis laukas veikia jame judančią elektringąją dalelę arba kūną. atitikmenys: angl. Lorentz force vok. Lorentz Kraft, f rus. лоренцова сила, f; сила… … Penkiakalbis aiškinamasis metrologijos terminų žodynas
Lorentz force — Lorenco jėga statusas T sritis fizika atitikmenys: angl. Lorentz force vok. Lorentzsche Kraft, f rus. сила Лоренца, f pranc. force de Lorentz, f … Fizikos terminų žodynas
Lorentz force — noun the force experienced by a point charge moving along a wire that is in a magnetic field; the force is at right angles to both the current and the magnetic field the Lorentz force can be used to suspend a current carrying object between two… … Useful english dictionary
Lorentz force — noun Physics the force exerted by a magnetic field on a moving electric charge. Origin 1930s: named after the Dutch theoretical physicist Hendrik Antoon Lorentz … English new terms dictionary
Lorentz force — /ˈlɒrənts fɔs/ (say loruhnts faws) noun the sum of the electric and magnetic forces on a moving electric charge. {from Hendrik Antoon Lorentz, 1853–1928, Dutch physicist} … Australian English dictionary
Lorentz force — noun the force exerted on a charged particle in an electromagnetic field … Wiktionary
Lorentz force density — Lorenco jėgos tankis statusas T sritis fizika atitikmenys: angl. Lorentz force density vok. Lorentzsche Kraftdichte, f rus. плотность силы Лорентца, f pranc. densité de force de Lorentz, f … Fizikos terminų žodynas
AbrahamLorentz force — In the physics of electromagnetism, the Abraham Lorentz force is the recoil force on an accelerating charged particle caused by the particle emitting electromagnetic radiation. It is also called the radiation reaction force. The formula for the… … Wikipedia
Lorentz — may refer to:In literature:* Friedrich Lorentz, author of works on the Pomeranian language * Pare Lorentz (1905 1992), American author and film directorIn physics:* Hendrik Lorentz (1853–1928), Dutch physicist and Nobel Prize winner * Lorentz… … Wikipedia