An Etymological Dictionary of Astronomy and Astrophysics

فرهنگ ریشه شناختی اخترشناسی-اخترفیزیک

M. Heydari-Malayeri    -    Paris Observatory



<< < alt sat > >>

Number of Results: 24 Search : current
alternating current (AC)
  جریان ِ پیوارنده   
jarayân-e peyvârandé

Fr.: courant alternatif   

An → electric current that reverses direction of flow at regular intervals. The typical alternating current is → sinusoidal in shape. Alternating current has the advantage over → direct current in that its → voltage magnitude can be changed easily through a → transformer. Moreover, it is safer to transfer over the longer city distances and can provide more → power. The frequency of alternating current is 50 Hz (Europe) or 60 Hz (USA).

alternating; → current.


Fr.: concourant   

1) Existing, happening, or done at the same time.
2) Acting in conjunction; cooperating. → concurrent forces.

Verbal adj. from → concur.

concurrent forces
  نیروهای ِ هاتزنده   
niruhâ-ye hâtazandé

Fr.: forces concourantes   

A system of forces applied to a → rigid body in such manner that their lines of action intersect at a single point. A system of concurrent forces acting on a rigid body can be replaced by an equivalent force applied at the same point. → line of action.

concurrent; → force.

jarayân (#)

Fr.: courant   

Any steady movement of material in space. In particular, any movement of electric charge. → stream; → flow; → flux.

From O.Fr. corant "running," pr.p. of courre "to run," from L. currere "to run," from PIE *kers- "to run" (cf. Gk. -khouros "running," Lith. karsiu "go quickly," O.N. horskr "swift," Welsh carrog "torrent").

Jarayân from Ar.

current cosmological epoch
  زیمه‌ی ِ کیهانشناختی ِ کنونی   
zime-ye keyhânšenâxti-ye konuni

Fr.: époque cosmologique actuelle   

The → Universe at the → redshift z = 0.

current; → cosmological; → epoch.

current density
  چگالی ِ جریان   
cagâli-ye jarayân

Fr.: densité de courant   

The electric current per unit of cross-sectional area perpendicular to the direction of current flow. It is a vector quantity and represented by symbol J. Electric current density is usually expressed in amperes per square meter.

current; → density

dark current
  جریان ِ تاریکی   
jarayân-e târiki

Fr.: courant d'obscurité   

Current generated in an electronic detector by thermal effects, even in the absence of input signal. In a → CCD detector, the current rises from thermal energy within the silicon lattice comprising the CCD. These electrons are captured by the CCD's potential wells and counted as signal. → dark current noise.

dark; → current.

dark current noise
  نوفه‌ی ِ جریان ِ تاریکی   
nufe-ye jarayân-e târiki

Fr.: bruit du courant d'obscurité   

In a → CCD detector, statistical fluctuation of the → dark current, equal to the square root of the dark current. CCDs can be cooled either with thermoelectric coolers or liquid nitrogen to reduce this effect. Ideally, the dark current noise should be reduced to a point where its contribution is negligible over a typical exposure time.

dark; → current; → noise.

direct current (DC)
  جریان ِ سرراست   
jarayân-e sarrâst

Fr.: courant continu   

An → electric current which flows in one direction only and which is substantially constant in magnitude. Virtually all electronic and computer hardware needs direct current to function. → Alternating current can be converted to direct current by means of a power supply consisting of a → transformer.

direct; → current.

displacement current
  جریان ِ جا-به-جایی   
jarayân-e jâ-be-jâyi (#)

Fr.: courant de déplacement   

In electromagnetism, a quantity which is not a real current (movement of charge), but has the units of current and has an associated magnetic field. The physical meaning of this displacement current is that a changing electric field makes a changing magnetic field.

displacement; → current.

eddy current
  جریان ِ فوکو   
jarayân-e Foucault (#)

Fr.: courant de Foucault   

An induced current circulating in masses of metal moving in a magnetic field or located in a changing magnetic field. Also known as → Foucault current.

eddy; → current.

electric current
  جریان ِ برق   
jarayân-e barq (#)

Fr.: courant électrique   

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

electric; → current.

Foucault current
  جریان ِ فوکو   
jarayân-e Foucault (#)

Fr.: courant de Foucault   

Same as → eddy current.

Foucault; → current.

galvanic current
  جریان ِ گالوانی   
jarayân-e gâlvâni

Fr.: courant galvanique   

The direct electric current that flows between metals or conductive nonmetals in a → galvanic couple.

galvanism; → current.

Humboldt current
  جریان ِ هومبولت   
jarayân-e Humboldt (#)

Fr.: courant de Humboldt   

A cold ocean current that flows northward along the western side of South America, offshore Chile and Peru. Dominate weather in this area includes coastal fog and low clouds. The presence or lack of this current is a vital part of the weather pattern known as El Niño.

Named after the German naturalist and explorer Alexander von Humboldt (1769-1859). → current.

induced current
  جریان ِ درهازیده، ~ ِ درهاخته   
jarayân-e darhâzidé, ~ darhâxté

Fr.: courant induit   

Current resulting from the relative motion of a conductor through a magnetic field.

induced ; → current.

intermittent current
  جریان ِ رفت-و-ماندی   
jarayân-e raftomândi

Fr.: courant intermittent   

A unidirectional electric current that flows and ceases to flow at irregular or regular intervals.

intermittent; → current.

photoelectric current
  جریان ِ شید-برقی   
jarayân-e šid-barqi

Fr.: courant photoélectrique   

The current produced in an → photoelectric effect process when → photoelectrons are received at the positive electrode.

photoelectric; → current.


Fr.: récurrent   

Occurring or appearing again, especially repeatedly or periodically ( → recurrence nova.

Verbal adj. from → recur.

recurrent nova
  نووای ِ باز‌آیند، نو‌اختر ِ ~   
novâ-ye bâzâyand, now-axtar-e ~

Fr.: nova récurrente   

A → cataclysmic variable star that undergoes → outbursts similar to those found in novae.

recurrent; → nova.

<< < alt sat > >>