kârâyi-ye turi (#)
Fr.: efficacité de réseau
The measure of the light intensity diffracted from a grating.
šiyâr-e turi (#)
Fr.: trait du réseau, sillon ~ ~
One of thousands of long, narrow indentations in the surface of a → diffraction grating.
To move or tend to move under the influence of gravitational force.
From L. gravitatus, p.p. of gravitâre, from gravis "heavy," → gravity.
Gerânidan, infinitive of gerân, → gravity.
1) The universal phenomenon of attraction between material bodies.
→ Newton's law of gravitation.
Verbal noun of → gravitate.
Of or relating to or caused by → gravitation.
Adj. of → gravitation.
šetâb-e gerâneši (#)
Fr.: accélération gravitationnelle
The acceleration caused by the force of gravity. At the Earth's surface it is determined by the distance of the object form the center of the Earth: g = GM/R2, where G is the → gravitational constant, and M and R are the Earth's mass and radius respectively. It is approximately equal to 9.8 m s-2. The value varies slightly with latitude and elevation. Also known as the → acceleration of gravity.
Fr.: attraction gravitationnelle
The force that pulls material bodies toward one another because of → gravitation.
rombeš-e gerâneši (#)
Fr.: effondrement gravitationnel
Collapse of a mass of material as a result of the mutual → gravitational attraction of all its constituents.
pâyâ-ye gerâneši (#)
Fr.: constante gravitationnelle
A fundamental constant that appears in → Newton's law of gravitation. It is the force of attraction between two bodies of unit mass separated by unit distance: G = 6.673 x 10-8 dyn cm2 g-2 or 6.673 x 10-8 cm3s-2g-1, or 6.673 x 10-11 N m2 kg-2 or 6.673 x 10-11 m3s-2kg-1. It was first measured in 1798 by Henry Cavendish (1731-1810), 71 years after Newton's death. Same as the → Newtonian constant of gravitation.
Fr.: contraction gravitationnelle
Decrease in the volume of an astronomical object under the action of a dominant, central gravitational force.
gravitational coupling constant
pâyâ-ye jafsari-ye gerâneši
Fr.: constante de couplage gravitationnel
The dimensionless gravitational constant defined as the gravitational attraction between pair of electrons and normally given by: αG = (Gme2) / (ħc) = (me / mP)2 ~ 1.7518 × 10-45, where ħ is → Planck's reduced constant, c the → speed of light, me is the → electron mass, and mP is the → Planck mass.
Fr.: rencontre gravitationnelle
An encounter in which two moving bodies alter each other's direction and velocity by mutual → gravitational attraction.
Fr.: énergie gravitationnelle
Same as → gravitational potential energy.
tarâzmandi-ye gerâneši (#)
Fr.: équilibre gravitationnel
The condition in a celestial body when gravitational forces acting on each point are balanced by some outward pressure, such as radiation pressure or electron degeneracy pressure, so that no vertical motion results.
meydân-e gerâneši (#)
Fr.: champ gravitationnel
The region of space in which → gravitational attraction exists.
niru-ye gerâneši (#)
Fr.: force gravitationnelle
nâpâydâri-ye gerâneši (#)
Fr.: instabilité gravitationnelle
The process by which fluctuations in an infinite medium of size greater than a certain length scale (the Jeans length) grow by self-gravitation.
Fr.: interaction gravitationnelle
Mutual attraction between any two bodies that have mass.
adasi-ye gerâneši (#)
Fr.: lentille gravitationnelle
A concentration of matter, such as a galaxy or a cluster of galaxies, that bends light rays from a background object, resulting in production of multiple images. If the two objects and the Earth are perfectly aligned, the light from the distant object appears as a ring from Earth. This is called an Einstein Ring, since its existence was predicted by Einstein in his theory of general relativity.
gravitational lens equation
hamugeš-e adasi-ye gerâneši
Fr.: équation de lentille gravitationnelle
The main equation of gravitational lens theory that sets a relation between the angular position of the point source and the observable position of its image.