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Hertz The HERTZ (symbol: Hz) is the derived unit of frequency in the International System of Units International System of Units (SI) and is defined as one cycle per second . It is named for Heinrich Rudolf Hertz Hertz , the first person to provide conclusive proof of the existence of electromagnetic waves . Hertz Hertz are commonly expressed in multiples : kilohertz (103 Hz, kHz), megahertz (106 Hz, MHz), gigahertz (109 Hz, GHz), and terahertz (1012 Hz, THz). Some of the unit's most common uses are in the description of sine waves and musical tones , particularly those used in radio  and audiorelated applications. It is also used to describe the speeds at which computers and other electronics are driven. CONTENTS * 1 Definition * 2 History * 3 Applications * 3.1 Vibration * 3.2 Electromagnetic radiation * 3.3 Computers * 4 SI multiples * 5 See also * 6 Notes and references * 7 External links DEFINITIONThe hertz is equivalent to cycles per second , i.e., "1/second" or s 1 {displaystyle {text{s}}^{1}} [...More...]  "Hertz" on: Wikipedia Yahoo 

Hertz (other) The HERTZ (Hz) is the SI unit of frequency. HERTZ may also refer to: * Heinrich Hertz , (1857–1894), a German physicist * Hertz (surname) * Hertz (crater) , on Moon * Franck– Hertz experiment , fundamental physics * The Hertz Corporation , a car and equipment rental serviceSEE ALSO * Everybody Hertz , an album by Air * Herz (other) * Herts, an abbreviation of Hertfordshire * 52hertz whale This disambiguation page lists articles associated with the title HERTZ. If an internal link led you here, you may wish to change the link to point directly to the intended article. Retrieved from "https://en.wikipedia.org/w/index.php?title=Hertz_(other) additional terms may apply. By using this site, you agree to the Terms of Use and Privacy Policy .® is a registered trademark of the Wikimedia Foundation, Inc [...More...]  "Hertz (other)" on: Wikipedia Yahoo 

Hz (other) HZ is the International Standard symbol for Hertz , a unit of frequency. HZ may also stand for: * HZ (character encoding) * Habitable zone , the distance from a star where a planet can maintain Earthlike life * Hazard , a situation that poses a level of threat * Haze , in meteorology, METAR code HZ * Herero language (ISO 639 alpha2) * Herpes zoster , the shingles virus * Holden HZ , an automobile produced by General Motors Holden in the late 1970s * Hrvatske Željeznice , the Croatian national railway (HŽ) * SAT Airlines (IATA airline designator) * Saudi Arabia (aircraft registration code) * Croatian Railways (Hrvatske željeznice, HŽ) This disambiguation page lists articles associated with the title HZ. If an internal link led you here, you may wish to change the link to point directly to the intended article. Retrieved from "https://en.wikipedia.org/w/index.php?title=HZ additional terms may apply. By using this site, you agree to the Terms of Use and Privacy Policy .® is a registered trademark of the Wikimedia Foundation, Inc [...More...]  "Hz (other)" on: Wikipedia Yahoo 

Megahertz (other) MEGAHERTZ may refer to: * 1,000,000 Hertz (the SI unit of frequency) * Megahertz (horse) , a Thoroughbred racehorse * Megahertz (record producer) , American record producer, composer and songwriter This disambiguation page lists articles associated with the title MEGAHERTZ. If an internal link led you here, you may wish to change the link to point directly to the intended article. Retrieved from "https://en.wikipedia.org/w/index.php?title=Megahertz_(other) additional terms may apply. By using this site, you agree to the Terms of Use and Privacy Policy .® is a registered trademark of the Wikimedia Foundation, Inc [...More...]  "Megahertz (other)" on: Wikipedia Yahoo 

System Of Measurement A SYSTEM OF MEASUREMENT is a collection of units of measurement and rules relating them to each other. Systems of measurement have historically been important, regulated and defined for the purposes of science and commerce . Systems of measurement in modern use include the metric system , the imperial system , and United States United States customary units . CONTENTS* 1 History * 1.1 Current practice * 2 Metric system * 3 Imperial and US customary units * 4 Natural units * 5 Nonstandard units * 5.1 Area * 5.2 Energy Energy * 6 Units of currency * 7 Historical systems of measurement * 7.1 Africa * 7.2 Asia * 7.3 Europe * 7.4 North America * 7.5 Oceania * 7.6 South America * 8 See also * 8.1 Conversion tables * 9 Notes and references * 10 Bibliography * 11 External links HISTORY Main article: History of measurement The French Revolution gave rise to the metric system , and this has spread around the world, replacing most customary units of measure. In most systems, length (distance), mass , and time are _base quantities_. Later science developments showed that either electric charge or electric current could be added to extend the set of base quantities by which many other metrological units could be easily defined. (However, electrical units are not necessary for such a set [...More...]  "System Of Measurement" on: Wikipedia Yahoo 

SI Derived Unit The International System of Units (SI) specifies a set of seven base units from which all other SI units of measurement are derived. These SI DERIVED UNITS are either dimensionless , or can be expressed as a product of one or more of the base units, possibly scaled by an appropriate power of exponentiation . Many derived units do not have special names. For example, the SI derived unit of area is the square metre (m2) and the SI derived unit of density is the kilogram per cubic metre (kg/m3 or kg m−3). However, 22 derived units are recognized by the SI with special names, which are written in lowercase. However, the symbols for units named after persons, are always written with an uppercase initial letter. For example, the symbol for the hertz is "Hz"; but the symbol for the metre is "m". CONTENTS * 1 Derived units with special names * 2 Examples of derived quantities and units * 3 Other units used with SI * 4 Supplementary units * 5 See also * 6 References * 7 Bibliography DERIVED UNITS WITH SPECIAL NAMESThe International System of Units assigns special names to 22 derived units, which includes two dimensionless derived units, the radian (rad) and the steradian (sr) [...More...]  "SI Derived Unit" on: Wikipedia Yahoo 

Frequency FREQUENCY is the number of occurrences of a repeating event per unit time . It is also referred to as TEMPORAL FREQUENCY, which emphasizes the contrast to spatial frequency and angular frequency . The PERIOD is the duration of time of one cycle in a repeating event, so the period is the reciprocal of the frequency. For example, if a newborn baby's heart beats at a frequency of 120 times a minute, its period—the time interval between beats—is half a second (that is, 60 seconds divided by 120 beats ). Frequency is an important parameter used in science and engineering to specify the rate of oscillatory and vibratory phenomena, such as mechanical vibrations, audio (sound ) signals, radio waves , and light . CONTENTS * 1 Definitions * 2 Units * 3 Period versus frequency * 4 Related types of frequency * 5 In wave propagation * 6 Measurement * 6.1 Counting * 6.2 Stroboscope * 6.3 Frequency counter * 6.4 Heterodyne methods * 7 Examples * 7.1 Light * 7.2 Sound * 7.3 Line current * 8 See also * 9 Notes and references * 10 Further reading * 11 External links DEFINITIONS As time elapses—here moving left to right on the horizontal axis—the five sinusoidal waves vary, or cycle, regularly at different rates [...More...]  "Frequency" on: Wikipedia Yahoo 

Heinrich Hertz HEINRICH RUDOLF HERTZ (German: ; 22 February 1857 – 1 January 1894) was a German physicist who first conclusively proved the existence of the electromagnetic waves theorized by James Clerk Maxwell 's electromagnetic theory of light . The unit of frequency — cycle per second — was named the "hertz " in his honor. CONTENTS* 1 Biography * 1.1 Death * 2 Scientific work * 2.1 Meteorology * 2.2 Contact mechanics * 2.3 Electromagnetic waves * 2.4 Cathode rays * 3 Nazi persecution * 4 Legacy and honors * 5 See also * 6 References * 7 Further reading * 8 External links BIOGRAPHYHeinrich Rudolf Hertz was born in 1857 in Hamburg , then a sovereign state of the German Confederation , into a prosperous and cultured Hanseatic family. His father Gustav Ferdinand Hertz (originally named David Gustav Hertz) (1827–1914) was a barrister and later a senator . His mother was Anna Elisabeth Pfefferkorn. Hertz's father converted from Judaism to Christianity in 1834. His mother's family was a Lutheran pastor's family. While studying at the Gelehrtenschule des Johanneums in Hamburg, Hertz showed an aptitude for sciences as well as languages, learning Arabic and Sanskrit [...More...]  "Heinrich Hertz" on: Wikipedia Yahoo 

SI Base Unit The International System of Units International System of Units (SI) defines seven units of measure as a basic set from which all other SI units can be derived . The SI BASE UNITS and their physical quantities are the metre for measurement of length , the kilogram for mass , the second for time , the ampere for electric current , the kelvin for temperature , the candela for luminous intensity , and the mole for amount of substance . The SI base units form a set of mutually independent dimensions as required by dimensional analysis commonly employed in science and technology. The names and symbols of SI base units are written in lowercase, except the symbols of those named after a person, which are written with an initial capital letter. For example, the metre (US English: meter) has the symbol m, but the kelvin has symbol K, because it is named after Lord Kelvin Kelvin and the ampere with symbol A is named after AndréMarie Ampère AndréMarie Ampère . Other units, such as the litre (US English: liter), are formally not part of the SI, but are accepted for use with SI [...More...]  "SI Base Unit" on: Wikipedia Yahoo 

Second The SECOND (symbol: S) (abbreviated S or SEC) is the base unit of time in the International System of Units International System of Units / Système International d'Unités (SI). It is qualitatively defined as the second division of the hour by sixty, the first division by sixty being the minute . The SI definition of second is "the duration of 9 192 631 770 periods of the radiation corresponding to the transition between the two hyperfine levels of the ground state of the caesium 133 atom". Seconds may be measured using a mechanical, electrical or an atomic clock . SI prefixes are combined with the word second to denote subdivisions of the second, e.g., the millisecond (one thousandth of a second), the microsecond (one millionth of a second), and the nanosecond (one billionth of a second). Though SI prefixes may also be used to form multiples of the second such as kilosecond (one thousand seconds), such units are rarely used in practice. The more common larger nonSI units of time are not formed by powers of ten; instead, the second is multiplied by 60 to form a minute, which is multiplied by 60 to form an hour , which is multiplied by 24 to form a day . The second is also the base unit of time in other systems of measurement : the centimetre–gram–second , metre–kilogram–second , metre–tonne–second , and foot–pound–second systems of units [...More...]  "Second" on: Wikipedia Yahoo 

Multiplicative Inverse In mathematics , a MULTIPLICATIVE INVERSE or RECIPROCAL for a number x, denoted by 1/x or x−1, is a number which when multiplied by x yields the multiplicative identity , 1. The multiplicative inverse of a fraction a/b is b/a. For the multiplicative inverse of a real number, divide 1 by the number. For example, the reciprocal of 5 is one fifth (1/5 or 0.2), and the reciprocal of 0.25 is 1 divided by 0.25, or 4. The RECIPROCAL FUNCTION, the function f(x) that maps x to 1/x, is one of the simplest examples of a function which is its own inverse (an involution ). The term reciprocal was in common use at least as far back as the third edition of Encyclopædia Britannica (1797) to describe two numbers whose product is 1; geometrical quantities in inverse proportion are described as reciprocall in a 1570 translation of Euclid Euclid 's Elements . In the phrase multiplicative inverse, the qualifier multiplicative is often omitted and then tacitly understood (in contrast to the additive inverse ). Multiplicative inverses can be defined over many mathematical domains as well as numbers. In these cases it can happen that ab ≠ ba; then "inverse" typically implies that an element is both a left and right inverse . The notation f −1 is sometimes also used for the inverse function of the function f, which is not in general equal to the multiplicative inverse [...More...]  "Multiplicative Inverse" on: Wikipedia Yahoo 

International System Of Units The INTERNATIONAL SYSTEM OF UNITS (abbreviated as SI, from the French _Système internationale (d'unités)_) is the modern form of the metric system , and is the most widely used system of measurement . It comprises a coherent system of units of measurement built on seven base units . The system also establishes a set of twenty prefixes to the unit names and unit symbols that may be used when specifying multiples and fractions of the units. The system was published in 1960 as a result of an initiative that began in 1948. It is based on the metre–kilogram–second system of units (MKS) rather than any variant of the centimetre–gram–second system (CGS). SI is intended to be an evolving system, so prefixes and units are created and unit definitions are modified through international agreement as the technology of measurement progresses and the precision of measurements improves. The 24th and 25th General Conferences on Weights and Measures (CGPM) in 2011 and 2014, for example, discussed a proposal to change the definition of the kilogram , linking it to an invariant of nature rather than to the mass of a material artefact, thereby ensuring longterm stability. The motivation for the development of the SI was the diversity of units that had sprung up within the CGS systems and the lack of coordination between the various disciplines that used them [...More...]  "International System Of Units" on: Wikipedia Yahoo 

Cycle Per Second The CYCLE PER SECOND was a oncecommon English name for the unit of frequency now known as the hertz . The plural form was typically used, often written CYCLES PER SECOND, CYCLES/SECOND, C.P.S., C/S, ~, or, ambiguously, just CYCLES. The term comes from the fact that sound waves have a frequency measurable in their number of vibrations, or _cycles_, per second. With the organization of the International System of Units in 1960, the cycle per second was officially replaced by the hertz , or reciprocal second . Symbolically, "cycle per second" units are "cycle/second", while hertz is "1/s" or "s−1". This particular mandate has been so widely adopted as to render the old 'cycle per second' all but extinct. For higher frequencies, _kilocycles_ (kc), as an abbreviation of _kilocycles per second_ were often used on components or devices. Other higher units like _megacycle_ (Mc) and less commonly _kilomegacycle_ (kMc) were used before 1960 and in some later documents. These have modern equivalents such as kilohertz (kHz), megahertz (MHz), and gigahertz (GHz). The rate at which aperiodic or stochastic events occur may be expressed in becquerels (as in the case of radioactive decay ), not hertz, since although the two are mathematically similar by convention hertz implies regularity where becquerels implies the requirement of a time averaging operation [...More...]  "Cycle Per Second" on: Wikipedia Yahoo 

Electromagnetic Wave In physics , ELECTROMAGNETIC RADIATION (EM RADIATION or EMR) refers to the waves (or their quanta, photons ) of the electromagnetic field , propagating (radiating) through space carrying electromagnetic radiant energy . It includes radio waves , microwaves , infrared , (visible) light , ultraviolet , X , and gamma radiation. Classically , electromagnetic radiation consists of ELECTROMAGNETIC WAVES, which are synchronized oscillations of electric and magnetic fields that propagate at the speed of light through a vacuum . The oscillations of the two fields are perpendicular to each other and perpendicular to the direction of energy and wave propagation, forming a transverse wave . The wavefront of electromagnetic waves emitted from a point source (such as a lightbulb) is a sphere . The position of an electromagnetic wave within the electromagnetic spectrum could be characterized by either its frequency of oscillation or its wavelength . The electromagnetic spectrum includes, in order of increasing frequency and decreasing wavelength: radio waves, microwaves, infrared radiation, visible light , ultraviolet radiation, Xrays and gamma rays . Electromagnetic waves are produced whenever charged particles are accelerated , and these waves can subsequently interact with other charged particles. EM waves carry energy , momentum and angular momentum away from their source particle and can impart those quantities to matter with which they interact [...More...]  "Electromagnetic Wave" on: Wikipedia Yahoo 

Metric Prefix A METRIC PREFIX is a unit prefix that precedes a basic unit of measure to indicate a multiple or fraction of the unit. While all metric prefixes in common use today are decadic , historically there have been a number of binary metric prefixes as well. Each prefix has a unique symbol that is prepended to the unit symbol. The prefix _kilo _, for example, may be added to _gram_ to indicate _multiplication_ by one thousand: one kilogram is equal to one thousand grams. The prefix _milli _, likewise, may be added to _metre_ to indicate _division_ by one thousand; one millimetre is equal to one thousandth of a metre. Decimal multiplicative prefixes have been a feature of all forms of the metric system , with six dating back to the system's introduction in the 1790s. Metric prefixes have even been prepended to nonmetric units. The SI PREFIXES are standardized for use in the International System of Units (SI) by the International Bureau of Weights and Measures (BIPM) in resolutions dating from 1960 to 1991. Since 2009, they have formed part of the International System of Quantities [...More...]  "Metric Prefix" on: Wikipedia Yahoo 
