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

The thirteenth known moon of Jupiter, discovered in 1905 by Charles Perrine.

In Gk. mythology, Elara was the mother by Zeus of the giant Tityus.

Of, pertaining to, or noting a body having the property of → elasticity. See also → elastic collision, → elastic deformation, → elastic limit, → elastic scattering.

From Fr., from Gk. elastos "ductile, flexible," related to elaunein "to strike, beat out."

Kešâyand, from keš stem of kešidan/kašidan "to pull, drag, draw" (Av. karš- "to draw, to plough," karša- "furrow;" cf. Skt. kars-, kársati "to pull, drag, plough," Gk. pelo, pelomai "to be busy, to bustle") + âyand agent form of âmadan "to come; to become," from Mid.Pers. âmatan (O.Pers. gam- "to come; to go," Av. gam- "to come; to go," jamaiti "goes;" O.Iranian *āgmatani; Skt. gamati "goes;" Gk. bainein "to go, walk, step;" L. venire "to come;" Tocharian A käm- "to come;" O.H.G. queman "to come;" E. come; PIE root *gwem- "to go, come").

A collision between two particles which conserves the total kinetic energy and momentum of the system.

→ elastic; → collision.

A deformation of a → solid body in which the change (→ strain) in the relative position of points in the body disappears when the deforming stress is removed. See also → elastic limit.

→ elastic; → deformation.

The smallest → stress beyond which a → solid body can no longer return to its original shape. The material ceases to obey → Hooke's law. Also called → yield point.

→ elastic; → limit.

In a → collision between two → particles, the reaction in which the total → kinetic energy of the system, projectile plus target, is the same before the collision as after.
In the interaction of → electromagnetic waves with particles, the scattering when the → wavelength (→ frequency) of the → scattered light is the same as the → incident light (→ Rayleigh scattering, → Mie scattering).

→ elastic; → scattering.

A wave that propagates by → elastic deformation of the medium. The → propagation takes place by a change in shape that disappears when the forces are removed. In other words, the displaced particles transfer momentum to adjoining particles, and are themselves restored to their original position. A → seismic wave is a type of elastic wave.

→ elastic; → wave.

The ability of a body which has been → deformed by an applied → force to return to its original shape when the force is removed. Up to a certain point the material obeys → Hooke's law. See also → ductility, → plasticity.

→ elastic + → -ity.

The joint of the human → arm between the → upper arm and the → forearm.

M.E. elbowe, from O.E. elboga, elnboga, from ell + bow. Cognate with Scots elbuck, Du. elleboog, Ger. Ellbogen, Ellenbogen, Dan. albue, Icelandic olbogi, olnbogi "elbow."

Ârenj "elbow," variants âranj, âran "elbow," araš "forearm;" Mid.Pers. âranj, O.Pers. arašan- "cubit," Av. arəθnâ- "elbow," Skt. aratni- "elbow," Iranian stem aratan-, araθn-, borrowed from Iranian into General Slavic as aršin "ell."

Pertaining to, derived from, produced by, or associated with electricity.

Term coined in by the English physicist William Gilbert (1540-1603) in treatise De Magnete (1600), from L. electrum "amber," from Gk. elektron "amber."

Barqi, adj. of barq, → electricity.

A luminous and extremely hot electrical → discharge between two → electrodes when an ionized → plasma is created in the air or gas across the electrodes.

→ electric; → arc.

The intrinsic property of matter responsible for all electric phenomena, occurring in two forms arbitrarily designated → negative and → positive.

→ electric; → charge.

Physics: A closed path followed by an → electric current; a number of → conductors interconnected for the purpose of carrying an electric current.

→ electric; → circuit.

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.