Definition of Focis. Meaning of Focis. Synonyms of Focis

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Definition of Focis

Foci
Focus Fo"cus, n.; pl. E. Focuses, L. Foci. [L. focus hearth, fireplace; perh. akin to E. bake. Cf. Curfew, Fuel, Fusil the firearm.] 1. (Opt.) A point in which the rays of light meet, after being reflected or refrcted, and at which the image is formed; as, the focus of a lens or mirror. 2. (Geom.) A point so related to a conic section and certain straight line called the directrix that the ratio of the distace between any point of the curve and the focus to the distance of the same point from the directrix is constant. Note: Thus, in the ellipse FGHKLM, A is the focus and CD the directrix, when the ratios FA:FE, GA:GD, MA:MC, etc., are all equal. So in the hyperbola, A is the focus and CD the directrix when the ratio HA:HK is constant for all points of the curve; and in the parabola, A is the focus and CD the directrix when the ratio BA:BC is constant. In the ellipse this ratio is less than unity, in the parabola equal to unity, and in the hyperbola greater than unity. The ellipse and hyperbola have each two foci, and two corresponding directrixes, and the parabola has one focus and one directrix. In the ellipse the sum of the two lines from any point of the curve to the two foci is constant; that is: AG+GB=AH+HB; and in the hyperbola the difference of the corresponding lines is constant. The diameter which passes through the foci of the ellipse is the major axis. The diameter which being produced passes through the foci of the hyperbola is the transverse axis. The middle point of the major or the transverse axis is the center of the curve. Certain other curves, as the lemniscate and the Cartesian ovals, have points called foci, possessing properties similar to those of the foci of conic sections. In an ellipse, rays of light coming from one focus, and reflected from the curve, proceed in lines directed toward the other; in an hyperbola, in lines directed from the other; in a parabola, rays from the focus, after reflection at the curve, proceed in lines parallel to the axis. Thus rays from A in the ellipse are reflected to B; rays from A in the hyperbola are reflected toward L and M away from B. 3. A central point; a point of concentration. Aplanatic focus. (Opt.) See under Aplanatic. Conjugate focus (Opt.), the focus for rays which have a sensible divergence, as from a near object; -- so called because the positions of the object and its image are interchangeable. Focus tube (Phys.), a vacuum tube for R[oe]ntgen rays in which the cathode rays are focused upon the anticathode, for intensifying the effect. Principal, or Solar, focus (Opt.), the focus for parallel rays.

Meaning of Focis from wikipedia

- et Focis is the motto for Maritzburg College, a high school in South Africa, and the motto is embedded in the school's shield. Pro Aris et PRO Focis was...
- Look up focus or foci in Wiktionary, the free dictionary. Focus (pl.: foci or focuses) may refer to: Focus or Focus Festival, former name of the Adelaide...
- The album contains eleven tracks almost all produced by himself and D. Focis, and only one song was produced by Junior Varsity. It features guest appearances...
- A hypocenter or hypocentre (from Ancient Gr**** ὑπόκεντρον (hupókentron) 'below the center'), also called ground zero or surface zero, is the point on the...
- or foci (/ˈfoʊkaɪ/; sg.: focus) are special points with reference to which any of a variety of curves is constructed. For example, one or two foci can...
- A focus of infection is a place containing whatever epidemiological factors are needed for transmission of an infection. Any focus of infection will have...
- Aberrant crypt foci (ACF) are clusters of abnormal tube-like glands in the lining of the colon and ****. Aberrant crypt foci form before colorectal...
- Bernoulli is a plane curve defined from two given points F1 and F2, known as foci, at distance 2c from each other as the locus of points P so that PF1·PF2...
- Tavoliere, also known as the "granary of Italy". The name "Foggia" (originally Focis) probably derives from Latin "fovea", meaning "pit", referring to the pits...
- further used on occasion to describe other curves having two singular points (foci), such as ellipses, hyperbolas, and C****ini ovals. However, the term bipolar...