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arc,in electricity, highly luminous and intensely hot discharge of electricity between two electrodes. The arc was discovered early in the 19th cent. by the English scientist Sir Humphry Davy, who so named it because of its shape. An arc is characterized by a high current, low voltage, and indefinite duration. It is usually started when two electrodes carrying an electric current are drawn apart. At the instant the electrodes are parted, strong electric forces draw electrons from one electrode to the other, initiating the arc. The discharge consists of a current composed of these electrons and charged gas particles, called ions, that form between the electrodes. The first practical electric light, the arc lamp, made use of the arc formed between two carbon rods (see lightinglighting,
light produced by artificial means to allow visibility in enclosures and at night. For stage lighting, see scene design and stage lighting. Early Sources of Artificial Lighting
..... Click the link for more information. ). Today the use of the arc lamp is limited to special purposes, e.g., in searchlights and in research applications. The principle of the electric arc is employed in weldingwelding,
process for joining separate pieces of metal in a continuous metallic bond. Cold-pressure welding is accomplished by the application of high pressure at room temperature; forge welding (forging) is done by means of hammering, with the addition of heat.
..... Click the link for more information. (as in the hydrogen arc, where hydrogen is introduced between tungsten electrodes) and also in generating heat in the electric furnace. A spark, like an arc, is a discharge of electricity between two points, but it has a high voltage and a short duration. Lightning is an example of a spark.
arc,in geometry, a curved line or any part of it; in particular, a portion of the circumference of a circle. The length s of an arc of a circle of radius r and subtending a central angle of θ radians is s=rθ; if θ is measured in degrees, then the arc is given by s=2πrθ/360.
ARCAbbrev. for Astrophysical Research Consortium. See Apache Point Observatory.
(also called simple arc or Jordan arc), a part of a curve that is contained between two of its points and does not have multiple points. The arc is more accurately defined on a plane, with the coordinates of its points being given as the continuous functions x = φ(t) and y = ψt of some parameter t, a ≤ t ≤ b. It is assumed that the different points correspond to the different values of t.
arc(file format, tool)
ARC(1) (Audio Return Channel) See HDMI ARC.
(2) PC compression programs from System Enhancement Associates, Inc., Clifton, NJ. ARC was one of the first compression utilities to become popular in the early 1980s. ARC+Plus provides enhanced features and speed.
(3) The ARC extension was previously used by PKWARE Inc. in its PKARC program.
(4) (Advanced RISC Computing) An earlier open system specification based on the MIPS R3000 and R4000 CPUs. It included EISA and TURBOchannel buses.