Definition of Focuses. Meaning of Focuses. Synonyms of Focuses

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Definition of Focuses

Focuses
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 Focuses from wikipedia

- Look up focus or foci in Wiktionary, the free dictionary. Focus, or its plural form foci may refer to: Focus or Focus Festival, former name of the Adelaide...
- Look up focusing in Wiktionary, the free dictionary. Focusing may refer to: Adjusting an optical system to minimize defocus aberration Focusing (psychotherapy)...
- InFocus Corporation is an American privately owned company based in the state of Oregon. Founded in 1986, the company develops, manufactures, and distributes...
- 2010. "Focus... Leaves Aftermath, Focuses on his label a.Fam Entertainment". The Hype Machine. May 25, 2009. Retrieved March 3, 2010. Focus… at AllMusic...
- Focus Plays Focus is the first studio album by Dutch rock band Focus, released in September 1970 on Imperial Records. It is the only album recorded by...
- FOCUS is a fourth-generation programming language (4GL) computer programming language and development environment that is used to build database queries...
- Look up focused in Wiktionary, the free dictionary. Focused may refer to: Focused (band), a Christian hardcore band Focused (album), a 1999 album by Billy...
- optics, a focus, also called an image point, is a point where light rays originating from a point on the object converge. Although the focus is conceptually...
- of the progressive rock band Focus consists of 11 studio albums, 1 compilation album, 6 live albums, and 8 singles. "Focus Album Top 100". Kent, David...
- lens's optical focus on whatever subject or action is being filmed. "Pulling focus" refers to the act of changing the camera lens's focus distance to a...