ELECTROSTATIC FIELD

From Big Medical Encyclopedia

ELECTROSTATIC FIELD (synonym static electric field) — electric field of motionless (static) electric charges. AA. the item represents a special form of electric field, a cut generally is a component of the electromagnetic field (see). The electrostatic field resulting from accumulation of electric charges on a body surface of the person possesses nonspecific action on an organism. At the heart of this action as believe, the neuroreflex mechanism lies (see. Static electricity), however certain disease E. the item does not cause in the person.

Power characteristic E. the item, as well as electric field, is tension (E) — vector size, cover a numerical value equally in the relation of force (F) operating in this point of the field on dot positive charge to the size (q) of this charge: Е = F/q.

Direction of tension E. the item matches the direction of this force. As well as electric field, AA. the item conditionally is submitted power lines, the direction of tangents to the Crimea matches the direction of a vector of tension E. the item in the same points of the field. Power lines E. items are oriented from positive charge to negative, their configuration depends on a form of surfaces, on to-rykh charges are located.

Power characteristic E. the item is potential φ, to-ry is equal to the relation of a potential energy (P) of interaction of a charge with E in each this point of the field. the item to the size of this charge: φ = P/q.

Practical value has potential difference, or tension (U), between two points of the field: U = φ 1 — φ 2 equal to the relation of the work (A) made by forces of the field during the movement of dot positive charge from one point E. the item in another, to the size of this charge: U = A/q. Values of potentials φ in various points E. the item can be presented in the form of surfaces of identical potential (equipotential surfaces). Equipotential surfaces and power lines in each point of electrostatic field are mutually perpendicular.

Tension E. the item (E) and its tension (U) are connected among themselves by the relation of E = U/L where L — distance along the power line between points E. the item, potential difference between to-rymi U is equal. This relation is used in practice for indirect measurement of tension electric and electrostatic water. Unit is the volt on meter (in oil). For homogeneous E. the item of the flat condenser E = U/d, where U — tension attached to plates of the condenser, and d — distance between them.

In placed in E. the item dielectric (the substance which is badly carrying electric current) happens the shift of charges within atom of substance (see Atom) either its molecules (see) or so-called polarization, as a result a cut on the surface of dielectric appear the connected charges and the return field corresponding to them weakening external E. the item (see Polyariaation). Ability of any dielectric to polarization is characterized by its dielectric permeability (see).

In the conductor which is in E. the item, happens movement of free charges until tension resulting E. the item in the conductor will not become equal to zero. In the space limited to the metal gauze, AA. the item is absent that is used for a hook naz. electrostatic protection: at certain inspections removal of the electroencephalogram and so forth), experiments or measurements of people, animals and devices place in the metal conductor (grid) which is grounded.

The person resides under the influence of E. item. It is caused by natural factors (the total static charge of Earth making 5,7*10^5 to causes near the Earth's surface E. the item tension about 130 in oil), production and household factors (see. Static electricity), and also can be caused by nek-ry medical procedures (see Franklinization).

Under the influence of E. the item happens polarization biol. the structures having dielectric properties and a nek-swarm movement of ions. Since tissues of the person generally have the expressed electroconductive properties, external E. the item in bodies almost does not get (see Conductivity of biological systems). The main action on the person external E. the item renders in connection with electric discharges in an ambient air and formation of aeroions (see Aeroionization).

Bibliography: Physical factors in complex treatment I to prevention of internal and nervous diseases, under the editorship of A. N. Obrosov, M., 1971. See also bibliogr. to St. Electromagnetic field .

A. N. Remizov.

Яндекс.Метрика