obtuse angle zâviye-ye bâz (#) Fr.: angle obtus An angle whose measure is greater than 90° and less than 180°. Obtuse, from M.Fr. obtus (fem. obtuse), from L. obtusus "blunted, dull," p.p. of obtundere "to beat against, make dull," from ob "against" + tundere "to beat," from PIE *(s)tud- "to beat, strike, push, thrust;" → angle. Zâviyé, → angle; bâz "open," from Mid.Pers. abâz-, apâc-, O.Pers. apa- [pref.] "away, from;" Av. apa- [pref.] "away, from," apaš [adv.] "toward the back;" cf. Skt. ápāñc "situated behind." |
parallactic angle zâviye-ye didgašti Fr.: angle parallactique Of an object in the sky, the angle between the → celestial pole, the object, and the → zenith. Since parallactic angle describes the orientation on the sky of the object for a particular observer, it can be an important quantity in some observations. → parallactic; → angle. |
parallax angle zâviye-ye didgašt Fr.: angle de parallaxe The angular displacement associated with → parallax. |
Pascal's triangle sebar-e Pascal Fr.: triangle de Pascal An array of numbers in the shape of a triangle, having a 1 at the top and also at the ends of each row. Each number is obtained by summing the two adjacent numbers to it in the preceding row. Each row is a set of → binomial coefficients. In the expansion of (x + y)^{n}, the coefficients of x and y are given by the n-th row of Pascal's traingle. |
phase angle zâviye-ye fâz (#) Fr.: angle de phase 1) Physics: Of a → periodic wave,
the number of suitable units of angular
measure between a point on the wave and a reference point. |
polarization angle zâviye-ye qotbeš (#) Fr.: angle de polarisation Same as → polarizing angle and → Brewster angle. → polarization; → angle. |
polarizing angle zâviye-ye qotbeš (#) Fr.: angle de polarisation The angle of → incidence for which the reflected light is completely polarized. Also called the → Brewster angle and → polarization angle. See also → Brewster's law. |
position angle zâviye-ye neheš Fr.: angle de position The convention for measuring angles on the sky in astronomy (Abbreviated as PA). It is the direction of an imaginary arrow in the sky, measured from north through east: 0° = north, 90° = east, 180° = south, and so on to 359° and back to 0°. Applied to a binary system it is the direction of a secondary body or feature from a primary, measured in the system. . |
prism angle zâviye-ye manšur Fr.: angle de prisme The angle between the faces on which light is incident and from which it emerges. |
quadrangle cahârgušé, cârguš Fr.: quadrilatère A two-dimensional figure that consists of four points connected by straight lines. Same as → tetragon; see also → quadrilateral. L.L. quadrangulum, noun use of neuter of L. quadrangulus, quadriangulus "four-cornered," from quadr- variant of quadri- before a vowel "four," akin to quattuor, → four, cognate with Pers. cahâr, as below; → angle. Cahârgušé, cârguš "four-cornered," from cahâr, câr "four," cognate with L. quattuor, → four, + gušé, guš "corner, angle;" Mid.Pers. gôšak "corner." |
quantum entanglement ham-gureš-e kuântomi, ham-pici-ye ~ Fr.: emmêlement quantique, intrication ~ A quantum → phenomenon that occurs when two or more particles (→ photons or → atomic particles) that have a common origin remain linked together when they travel apart. A measurement of one of the particles determines not only its → quantum state but the quantum state of the other particle as well. A change in one is instantly reflected in the other. To use a familiar example, it is as if you have a pair of dice entangled in such a way that when you throw them the sum of the two is 7. Any time you cast them, if the first die shows 2, 5, 3, etc. the other will show 5, 2, 4, etc., respectively. Quantum entanglement is rooted in the → superposition principle. But, in contrast to → quantum coherence, the states in a superposition are the shared states of two entangled particles rather than those of the two split waves of a single particle. There are several ways for entangling atomic particles. Photons can be entangled using → cascade transitions, as was done by Alain Aspect and colleagues in the early 1980s (→ Aspect experiment). Calcium atoms are put into a highly-excited energy level where the electron is forbidden to return to the → ground state by emitting a single photon. As a result, the atoms → decay by emitting two photons which are entangled. Like quantum coherence, quantum entanglement plays an essential role in quantum technologies, such as quantum teleportation, quantum cryptography, and super dense coding. See also → EPR paradox. → quantum; → entanglement. |
rainbow angle zâviye-ye rangin-kamân Fr.: angle d'arc-en-ciel The → obtuse angle between sunlight and the → line of sight. Rainbow angle = 180° minus → scattering angle. For the → primary rainbow it is 138°, and for the → secondary rainbow 130°. |
rectangle râstgušé (#) Fr.: rectangle A → quadrilateral all of whose angles are → right angles. M.Fr. rectangle, from M.L. rectangulum "a triangle having a right angle," from rect-, combining form of rectus→ right + angulum, → angle. Râstgušé, from râst, → right, + gušé "corner, angle;" Mid.Pers. gôšak "corner." |
Reuleaux triangle sebar-e Reuleaux Fr.: triangle de Reuleaux A shape of constant width created using an equilateral triangle and three similar circles. The equilateral triangle lies in the first circle with a vertex coinciding with the center of the circle and the sides equal to the circle radius. The centers of the two other circles are located at the two other vertices. The Reuleaux triangle is the intersection of the three circles. Named after Franz Reuleaux (1829-1905), a German engineer, specialist of analysis and design of mechines; → triangle. |
right angle zâviye-ye râst Fr.: angle droit An angle of 90°. |
right triangle sebar-e râst (#) Fr.: triangle droit A triangle one of whose angles is a → right angle. |
ring opening angle zâviye-ye gošâyeš-e halqé Fr.: angle d'ouverture des anneaux Of → Saturn, the angle between the line of sight and the ring plane. Also known as elevation angle, tilt angle. Zâviyé, → angle; gošâyeš "opening," verbal noun from gošudan, gošâdan "to open up, loose, let free;" gošâd "opened; ample, broad;" Mid.Pers. wišâdan "to let free;" Khotanese hīyā "bound;" O.Pers. višta "untied, loosened," vištāspa- "with loosened horses" (personal name); Av. višta "untied," ā-hišāiiā "holds fettered," hita- "fastened, tied on, put to;" cf. Skt. sā- "to bind, fasten, fetter," sitá- "bound," ví-sita- "untied;" halqé, → ring. |
scalene triangle sebar-e nâjur-pahlu Fr.: triangle scalène A triangle no two sides of which are equal. From L.L. scalenus, from Gk. skalenos "uneven, unequal, rough," from skallein "chop, hoe," related to skolios "crooked," from PIE base *(s)qel- "crooked, curved, bent;" → triangle. Sebar, → triangle; nâjur-pahlu "dissimilar sides," from nâjur "dissimilar, ill-matched" + pahlu "side, flank" (Mid.Pers. pahlug "side, rib," Av. pərəsu- "rib," Ossetic fars "side, flank," cf. Skt. párśu- "rib," Lith. piršys (pl.) "horse breast"). |
scattering angle zâvie-ye parâkaneš Fr.: angle de diffusion The angle between the → incident radiation on a → particle (such as a water droplet in a rainbow) and the scattered radiation (such as the light ray leaving the droplet). Scattering angle is a function of → impact parameter. In other words, The angle along which the change of direction has taken place, irrespective whether radiation is scattered by particles or reflected (refracted) by a surface. → scattering; → angle. |
shallow angle zâviye-ye nažal Fr.: angle faible Low angle, → grazing incidence. |