An Etymological Dictionary of Astronomy and Astrophysics
English-French-Persian

The → rate at which → electric charge → flows past a given point through a → conductor, measured in → amperes.

→ electric; → current.

1) A type of → charge distribution consisting of two charges, a positive and a negative charge of the same magnitude separated by a distance s, which is small compared to the distance r to the point P at which the → electric potential is V and the → electric field intensity is E.The potential falls as the square of the distance (1/r²) and the electric field intensity decreases as the cube of the distance (1/r³).
2) A simple → antenna consisting of a pair of oppositely charged → conductors capable of radiating an → electromagnetic wave in response to the movement of an electric charge from one conductor to the other.

→ electric; → dipole.

The flow of electricity through a gas, resulting in the emission of radiation that is characteristic of the gas and of the intensity of the current.

→ electric; → discharge.

The effect produced by the existence of an → electric charge in the volume of space that surrounds it. The direction of the field is taken to be the direction of the force it would exert on a positive test charge. The electric field is radially outward from a positive charge and radially in toward a negative point charge.

→ electric; → field.

The strength of an electric field at any point as measured by the force exerted upon a unit positive charge placed at that point.

→ electric; → intensity.

An electric → charge distribution consisting of more than four → positive and → negative → electric charges located at a small distance from each other. The multipole concept is an extension of the → electric quadrupole. For the generalized multipole characterized by the letter l, the potential at a distance r varies as 1/r^{l + 1} and the field intensity as 1/r^{l + 2}.

→ electric; → multipole.

The amount of → work required to move a unit → electric charge from → infinity to a specific point against an → electric field. The → SI unit of electric potential is → joules per → coulomb, otherwise known as → volt.

→ electric; → potential.

A potential φ defined so that the → electric field  E is expressed by a combination of its → gradient and the variation of the → magnetic vector potential over time: E = -∇φ -∂A/∂t.

→ electric; → scalar; → potential.

Of, relating to, or concerned with electricity; electric.

→ electric + → -al.

A measure of a material's ability to conduct an electrical current. It is the reciprocal of the → resistivity. Conductivity is expressed by σ = ne²l/(2mv), where n is the number of electrons per cm³ volume of the → conductor, e is the → electron charge, l is the → mean free path, m is the → electron mass, and v is the arithmetic mean velocity of thermal motion of electrons at a given temperature.

→ electrical; → conductivity.

An arrangement of the various electrical energy sources with interconnected electrical devices.

→ electric; → network.

1) The physical phenomena arising from the behavior of → electrons and → protons that is caused by the → attraction of particles with opposite → charges and the → repulsion of particles with the same charge.
2) The → science of electric charges and → currents.
3) A → flow of electrons that is used to generate → light and → power electric devices.

From L. electrum "amber," from Gk. elektron "amber" + -ity a suffix used to form abstract nouns expressing state or condition.

Barq, Pers. term, used also in Ar. and Hebrew (barak "lightening"); variants in Pers.: varq, barx, balk, belak, bala; Lârestâni belak; Tabari, Lahijâni, Semnâni, Sorxeyi, Sangesari belk; Gilaki val; Lori beleyz; Kurd. bilese; Tokharian AB pâlk; Mid/Mod.Pers. bir "lightening," Mid.Pers. brâh "brilliance, splendour," br'z- "to shine, beam," Mod.Pers. barâz "beauty, grace, elegance;" Av. brāz- "to shine, beam; splendour," brazāiti "shines;" cf. Skt. bhrāj- "to shine, beam, sparkle," bhrajate "shines;" Gk. phlegein "to burn;" L. fulgere "to shine," fulmen "lightning," flagrare "to blaze, burn;" O.H.G. beraht "bright;" O.E. beorht "bright;" E. → bright; PIE base *bherəg-; *bhrēg- "to shine; white."

A combining form denoting → electric or → electricity in compound words, such as → electrostatic, → electrodynamics, → electromagnetic. Also, before a vowel, electr-.

From electr(ic) + -o-.

Barq-, or barq + -â-, → electric.

1) A conductor by means of which a current passes into or out of a medium. The positive electrode is called anode; the negative electrode is called cathode.
2) In a CCD detector, one of a series of parallel conducting plates which run across the device at right angles to the channels and subdivide a channel into pixels. The plates create an electric field within the semiconductor which therefore forms a storage site for photo-generated charges.

Coined by E. physicist and chemist Michael Faraday (1791-1867) from electro-, → electric, + Gk. hodos "way."

Referring to electrons in motion.

→ electro- + → dynamics.

The phenomena, science, and applications of moving electric charges, as contrasted with → electrostatics. More specifically, the branch of physics concerned with the → interaction of → electric currents with → magnetic fields and → electric fields or with other electric currents.

→ electro- + → dynamics.

A temporary magnet made by coiling wire around an → iron core. When current flows in the coil, or → solenoid, the iron becomes a → magnet. The electromagnet acts as a magnet only so long as the current is flowing in the solenoid.

→ electro-; → magnet.

Of or pertaining to electromagnetism or electromagnetic fields.

→ electro- + → magnetic

An → electromagnetic signal associated with the location on the sky and the time of a → gravitational wave event. The electromagnetic signal is predicted by models to be associated with the → merger of a → compact binary star system composed of two → neutron stars (NS) or a neutron star and a → black hole (BH). Accordingly, the gravitational waves are accompanied by a short-duration → gamma-ray burst (GRB) powered by the → accretion of material that remains in a → centrifugally supported → torus around the BH following the merger. NS-NS/BH-NS mergers are also predicted to be accompanied by a more isotropic counterpart, commonly known as a → kilonova. Kilonovae are day to week-long thermal, → supernova-like → transients, and are powered by the → radioactive decay of heavy, neutron-rich elements synthesized by the → r-process in the expanding merger ejecta (Li and Paczynski 1998). The first detection of an electromagnetic counterpart to gravitational waves belongs to → GW170817.

→ electromagnetic; → counterpart.

A region of space consisting of coupled electric and magnetic lines of force at each point, generated by time-varying currents and accelerated charges.

→ electromagnetic; → field.