electric dipole

electric dipole
Pair of equal and opposite electric charges, the centres of which do not coincide.

An atom in which the centre of the negative cloud of electrons has been shifted slightly away from the nucleus by an external electric field is an induced electric dipole. When the external field is removed, the atom loses its dipolarity. A water molecule, in which two hydrogen atoms are situated to one side of an oxygen atom, is a permanent electric dipole. The oxygen side is always slightly negative, the hydrogen side slightly positive.

* * *

▪ chemistry and physics
      pair of equal and opposite electric charges (electric charge) the centres of which are not coincident. An atom in which the centre of the negative cloud of electrons has been shifted slightly away from the nucleus by an external electric field constitutes an induced electric dipole. When the external field is removed, the atom loses its dipolarity. A water molecule (H2O), in which two hydrogen atoms stick out on one side and form together with the oxygen atom as vertex a 105° angle, constitutes a permanent electric dipole. The oxygen side of the molecule is always somewhat negative and the hydrogen side somewhat positive. An electric dipole may be large, too, such as a long straight wire used as a radio transmitting antenna on which electrons are impelled back and forth, making one end negative and the other positive with reversal of polarity every half cycle.

      In an electric field a dipole undergoes a torque, tending to rotate so that its axis becomes aligned with the direction of the electric field. The amount of torque, greatest when the dipole is at right angles to the electric field, depends not only on the strength of the electric field but also on the separation of the two electric charges and their magnitude. If each charge has a magnitude q and the distance from the centre of the negative charge to that of the positive charge is d, the product qd is defined as the electric dipole moment. Its magnitude indicates the maximum torque exerted upon a given electric dipole per unit value of the surrounding electric field in a vacuum. The electric dipole moment, a vector, is directed along the line from negative charge toward positive charge. Dipole moments tend to point along the direction of the surrounding electric field.

      Because electric dipole moment has dimensions of electric charge times displacement, its unit in the metre–kilogram–second system is the coulomb-metre; in the centimetre–gram–second system it is the esu-centimetre.

* * *


Universalium. 2010.

Игры ⚽ Нужна курсовая?

Look at other dictionaries:

  • electric dipole — elektrinis dipolis statusas T sritis Standartizacija ir metrologija apibrėžtis Dviejų priešingo ženklo vienodų, esančių tam tikru atstumu vienas nuo kito elektros krūvių darinys. atitikmenys: angl. electric dipole vok. elektrischer Dipol, m rus.… …   Penkiakalbis aiškinamasis metrologijos terminų žodynas

  • electric dipole — elektrinis dipolis statusas T sritis fizika atitikmenys: angl. electric dipole vok. elektrischer Dipol, m rus. электрический диполь, m pranc. dipôle électrique, m …   Fizikos terminų žodynas

  • Electric dipole moment — In physics, the electric dipole moment (or electric dipole for short) is a measure of the polarity of a system of electric charges. In the simple case of two point charges, one with charge {+}q and one with charge { }q, the electric dipole moment …   Wikipedia

  • electric dipole moment — elektrinis dipolinis momentas statusas T sritis Standartizacija ir metrologija apibrėžtis Dydis, išreiškiamas elektrinio dipolio bet kurio poliaus elektros krūvio absoliučiosios vertės ir atstumo tarp polių sandauga. atitikmenys: angl. dipole… …   Penkiakalbis aiškinamasis metrologijos terminų žodynas

  • electric dipole moment — elektrinis dipolinis momentas statusas T sritis Standartizacija ir metrologija apibrėžtis Vektorinis dydis, kurio vektorinė sandauga su elektrinio lauko stipriu lygi sukimo momentui (p · E = T); čia p – elektrinio dipolinio momento vektorius, E – …   Penkiakalbis aiškinamasis metrologijos terminų žodynas

  • electric dipole moment — elektrinis dipolinis momentas statusas T sritis Standartizacija ir metrologija apibrėžtis Vektorinis dydis, lygus dipolio teigiamojo elektros krūvio ir jo peties sandaugai. Matavimo vienetas – kulonmetras. Žymimas C · m. atitikmenys: angl. dipole …   Penkiakalbis aiškinamasis metrologijos terminų žodynas

  • electric dipole moment — noun the dipole moment in an electric dipole • Hypernyms: ↑dipole moment * * * Elect. a vector quantity associated with two equal charges of opposite sign separated by a specified distance, having magnitude equal to the product of the charge and… …   Useful english dictionary

  • electric dipole radiation — elektrinis dipolinis spinduliavimas statusas T sritis fizika atitikmenys: angl. electric dipole radiation vok. elektrische Dipolstrahlung, f rus. электрическое дипольное излучение, n pranc. rayonnement dipolaire électrique, m; rayonnement électro …   Fizikos terminų žodynas

  • electric dipole moment of molecule — molekulės elektrinis dipolio momentas statusas T sritis Standartizacija ir metrologija apibrėžtis Vektorinis dydis, apibūdinantis molekulės elektrines savybes. Jo ir elektrinio lauko stiprio vektorinė sandauga lygi jėgų dvejeto momentui: p · E =… …   Penkiakalbis aiškinamasis metrologijos terminų žodynas

  • electric dipole transition — elektrinis dipolinis šuolis statusas T sritis fizika atitikmenys: angl. electric dipole transition vok. elektrischer Dipolübergang, m rus. электрический дипольный переход, m pranc. transition électro dipolaire, f …   Fizikos terminų žodynas

Share the article and excerpts

Direct link
… Do a right-click on the link above
and select “Copy Link”