Fr.: densité relative
The ratio of the density of a substance to the density of a given reference material. For a solid or liquid, it is the density (at 20°C) relative to the maximum density of water (at 4°C). For a gas is its density divided by the density of hydrogen (or sometimes dry air) at the same temperature and pressure. Also called → specific density.
Fr.: erreur relative
The → absolute error divided by the true value x, that is: Δx/x. The result may be expressed as a percentile and is useful when we want to determine the error relative to the value of the exact quantity.
Fr.: fréquence relative
Statistics: The number of the occurrences of an event divided by the number of observations.
Fr.: humidité relative
The amount of moisture in the air compared to what the air can "hold" at that temperature. It is given by the ratio of the partial pressure of water vapor in the mixture to the saturated vapor pressure of water at a specific temperature.
Fr.: invariant relatif
A → relative tensor of order zero.
Fr.: perméabilité relative
relative refractive index
dišan-e šekasti-ye bâzâni
Fr.: indice de réfraction relatif
The ratio of the sine of the angle of incidence to the sine of the angle of refraction for a ray passing out of one of the media into the other.
relative sunspot number
šomâr-e bâzâni-ye hurlak
Fr.: nombre relatif de taches solaires
Fr.: tenseur relatif
A generalized tensor concept that is characterized by a → Jacobian matrix of transformation raised to a power called → weight of a tensor density. In practice, only relative tensors of weight 1 or -1 are used. The product of a relative tensor of weight -1 by another tensor of weight 1 is an → absolute tensor. Same as → tensor density.
Fr.: vecteur relatif
Fr.: vitesse relative
For two objects A and B, the velocity which B, supposing itself at rest, assigns to A.
In a relative manner; in relation to something else.
From → relative + -ly "-vâr, -âné."
The belief that truth is relative and may vary from individual to individual, from group to group, or from time to time, having no objective standard.
From → relative + -ism a suffix used in the formation of nouns denoting action or practice, state or condition, principles, doctrines, etc.
Bâzâni-bâvari, from bâzâni, → relative, + bâvari, from bâvar "belief" (Mid.Pers. wâbar "beleif;" Proto-Iranian *uar- "to choose; to convince; to believe;" cf. Av. var- "to choose; to convince" varəna-, varana- "conviction, faith;" O.Pers. v(a)r- "to choose; to convince;" Skt. vr- "to choose," vara- "choosing").
An adherent or advocate of relativism.
From → relative + -ist a suffix of nouns.
Adj. from → relativism.
1) Physics: Relating to the → relativity theory.
Fr.: aberration relativiste
The aberration of light for an object moving with
→ relativistic speed. In contrast to the classical case,
the → Lorentz transformation between the
→ rest frame of the observer and that of the object
must be used. Relativistic aberration is expressed by the equation:
cos φ' = (cos φ -
relativistic Doppler effect
oskar-e Doppler-e bâzânigimand
Fr.: effet Doppler relativiste
The Doppler effect when the relative motion of the source and the observer is comparable to the speed of light. In that case the classical Doppler formula should be corrected for effects of the special theory of relativity (Lorentz transformation).
Fr.: masse relativiste
In → special relativity, the mass that is assigned to a body in motion. Einstein demonstrated that the velocity of the observer has an effect on the way inertial mass is measured. The relativistic mass is expressed by mt = m0 / [1 - (v/c)2]1/2, where m0 is the → rest mass, v is the velocity, and c the → velocity of light. The experimental evidence for this phenomenon is observed in the mass of high-speed electrons accelerated by magnetic fields. This formula shows that it is impossible for a mass to be accelerated to the velocity of light in a vacuum.
Fr.: particule relativiste
A particle which has a speed comparable to the velocity of light.
Fr.: précession relativiste
A → general relativistic phenomenon in which the line joining the → apsides of an orbit gradually rotates in a → prograde direction. Also called the → orbital precession and → perihelion precession. Although the general relativistic precession of Mercury's orbit is extremely small, the similar precession observed in the orbit of the → binary pulsar PSR B1913+16 amounts to 4.23 degrees per year, i.e. 36,000 times greater than the → advance of perihelion of Mercury.