The hertz (symbol Hz) is the SI unit of frequency defined as the number of cycles per second of a periodic phenomenon. One of its most common uses is the description of the sine wave, particularly those used in radio and audio applications.

Definition

The hertz is equivalent to cycles per second. In defining the second the CIPM declared that "the standard to be employed is the transition between the hyperfine levels F = 4, M =  0 and F = 3, M = 0 of the ground state 2S_1/2 of the caesium 133 atom, unperturbed by external fields, and that the frequency of this transition is assigned the value 9 192 631 770 hertz" thereby effectively defining the hertz and the second simultaneously.

In English, hertz is used as a plural. As an SI unit, Hz can be prefixed; commonly used multiples are kHz (kilohertz, 10³ Hz), MHz (megahertz, 10⁶ Hz), GHz (gigahertz, 10⁹ Hz) and THz (terahertz, 10¹² Hz). One hertz simply means "one cycle per second" (typically that which is being counted is a complete cycle); 100 Hz means "one hundred cycles per second", and so on. The unit may be applied to any periodic event—for example, a clock might be said to tick at 1 Hz, or a human heart might be said to beat at 1.2 Hz. The "frequency" (activity) of aperiodic or stochastic events, such as radioactive decay, is expressed in becquerels.

name	Hertz
standard	SI derived unit
quantity	Frequency
symbol	Hz
namedafter	Heinrich Hertz
extralabel	In SI base units:
extradata	1 Hz 1/s }}

Even though angular velocity, angular frequency and hertz all have the dimensions of ''1/s'', angular velocity and angular frequency are ''not'' expressed in hertz, but rather in an appropriate angular unit such as radians per second. Thus a disc rotating at 60 revolutions per minute (rpm) is said to be rotating at either 2π rad/s ''or'' 1 Hz, where the former measures the angular velocity and latter reflects the number of ''complete'' revolutions per second. The conversion between a frequency ''f'' measured in hertz and an angular velocity ''ω'' measured in radians per second are: :$\backslash omega\; =\; 2\backslash pi\; f\; \backslash ,$ and $f\; =\; \backslash omega/(2\backslash pi)\; \backslash ,$.

History

The hertz is named after the German physicist Heinrich Hertz, who made important scientific contributions to the study of electromagnetism. The name was established by the International Electrotechnical Commission (IEC) in 1930. It was adopted by the General Conference on Weights and Measures (CGPM) (''Conférence générale des poids et mesures'') in 1960, replacing the previous name for the unit, ''cycles per second'' (cps), along with its related multiples, primarily ''kilocycles per second'' (kc/s) and ''megacycles per second'' (Mc/s), and occasionally ''kilomegacycles per second'' (kMc/s). The term ''cycles per second'' was largely replaced by ''hertz'' by the 1970s.

The term "gigahertz", most commonly used in computer processor clock rates and radio frequency (RF) applications, can be pronounced either , with a hard sound, or , with a soft (see giga-#Pronunciation). The prefix "giga-" is derived directly from the Greek "."

Applications

Vibration

Sound is a traveling wave which is an oscillation of pressure. Humans perceive frequency of sound waves as pitch. Each musical note corresponds to a particular frequency which can be measured in hertz. An infant's ear is able to perceive frequencies ranging from 20 Hz to 20,000 Hz; the average adult human can hear sounds between 20 Hz and 16,000 Hz. The range of ultrasound, high-intensity infrasound and other physical vibrations such as molecular vibrations extends into the megahertz range and well beyond.

Electromagnetic radiation

Electromagnetic radiation is often described by its frequency—the number of oscillations of the perpendicular electric and magnetic fields per second—expressed in hertz.

Radio frequency radiation is usually measured in kilohertz, megahertz, or gigahertz; this is why radio dials are commonly labeled with kHz, MHz, and GHz. Light is electromagnetic radiation that is even higher in frequency, and has frequencies in the range of tens (infrared) to thousands (ultraviolet) of terahertz. Electromagnetic radiation with frequencies in the low terahertz range, (intermediate between those of the highest normally usable radio frequencies and long-wave infrared light), is often called terahertz radiation. Even higher frequencies exist, such as that of gamma rays, which can be measured in exahertz. (For historical reasons, the frequencies of light and higher frequency electromagnetic radiation are more commonly specified in terms of their wavelengths or photon energies: for a more detailed treatment of this and the above frequency ranges, see electromagnetic spectrum.)

Computing

In computing, most central processing units (CPU) are labeled in terms of their clock rate expressed in megahertz or gigahertz (10⁹ hertz). This number refers to the frequency of the CPU's master clock signal ("Clock rate"). This signal is simply an electrical voltage which changes from low to high and back again at regular intervals. This signal is also referred to as a square wave. Hertz has become the primary unit of measurement accepted by the general populace to determine the performance of a CPU, but many experts have criticized this approach, which they claim is an easily manipulable benchmark. For home-based personal computers, the CPU has ranged from approximately 1 megahertz in the late 1970s (Atari, Commodore, Apple computers) to up to 6 GHz in the present (IBM POWER processors).

Various computer buses, such as the front-side bus connecting the CPU and northbridge, also operate at different frequencies in the megahertz range (for modern products).

CRT television and monitor refresh rates are measured in hertz.

SI multiples

Frequencies not expressed in hertz

Even higher frequencies are believed to occur naturally, in the frequencies of the quantum-mechanical wave functions of high-energy (or, equivalently, massive) particles, although these are not directly observable, and must be inferred from their interactions with other phenomena. For practical reasons, these are typically not expressed in hertz, but in terms of the equivalent quantum energy, which is proportional to the frequency by the factor of Planck's constant.

See also

Alternating current

Electronic tuner

Frequency changer

Normalized frequency

Orders of magnitude (frequency)

Radian per second

Signal bandwidth

References

External links

BIPM Cesium ion f_Cs definition

National Research Council of Canada: ''Generation of the Hz''

National Research Council of Canada: ''Cesium fountain clock''

National Physical Laboratory: ''Trapped ion optical frequency standards''

National Research Council of Canada: ''Optical frequency standard based on a single trapped ion''

National Research Council of Canada: ''Optical frequency comb''

One Hertz in Radians per Second (Google). Note, as of 06 May 2009 there is an error of 2$\backslash pi$.

Category:SI derived units Category:Units of frequency

ar:هرتز ast:Herciu zh-min-nan:Hz be:Герц, адзінка вымярэння be-x-old:Гэрц (адзінка вымярэньня) bo:ཧེར་ཚི། bs:Herc br:Hertz bg:Херц ca:Hertz cs:Hertz cy:Hertz da:Hertz de:Hertz (Einheit) et:Herts el:Χερτζ es:Hercio eo:Herco eu:Hertz fa:هرتز fr:Hertz fy:Hertz (ienheid) ga:Heirts gl:Hertz hak:Het-tsṳ̂ ko:헤르츠 hi:हर्ट्ज़ hr:Herc id:Hertz ia:Hertz it:Hertz he:הרץ jv:Hertz lv:Hercs lb:Hertz lt:Hercas hu:Hertz mk:Херц ml:ഹെർട്സ് mr:हर्ट्झ ms:Hertz nl:Hertz (eenheid) ja:ヘルツ no:Hertz nn:Hertz mhr:Герц (шотлымаш) pnb:ہرٹز pl:Herc pt:Hertz ro:Hertz ru:Герц (единица измерения) sq:Herci simple:Hertz sk:Hertz (jednotka) sl:Herc sr:Херц sh:Herc fi:Hertsi sv:Hertz ta:ஏர்ட்சு tt:Герц (үлчәү берәмлеге) th:เฮิรตซ์ tg:Ҳертс tr:Hertz (birim) uk:Герц ur:ہرٹز vi:Hertz zh-yue:赫茲 zh:赫兹

name	The Crystal Method
background	group_or_band
origin	Los Angeles, California, U.S.
genre	Alternative Dance, Chemical breaks, big beat, breakbeat, electronic dance music
years active	1993–present
label	Outpost, Geffen, V2, Tiny E
website	TheCrystalMethod.com
current members	Scott Heisler KirklandKen B. Jordan }}

The Crystal Method is an American electronic music duo that was created in Los Angeles, California by Ken Jordan and Scott Kirkland in the early 1990s. The Crystal Method's music has appeared in numerous TV shows, films, video games, and advertisements. Their best-selling album, ''Vegas'', was certified platinum in 2007.

Biography

The Crystal Method is made up of two members, Ken B. Jordan and Scott Heisler Kirkland. Both of them were born in Las Vegas, Nevada. Kirkland was born when his mother was only fifteen. He grew up listening to his mother's music—disco—and his father's music—rock. When he had grown a little older, he began listening to heavy metal, as well as bands like Depeche Mode. Ken Jordan also grew up listening to classic rock and '80s electronica.

Early days (1993–1995)

By the early '90s, both Ken and Scott had moved to Los Angeles. Before The Crystal Method was formed, Ken and Scott started working on music while working at the grocery store and while Ken was a local DJ in Las Vegas as well as the college radio program director at UNLV. Ken taught Scott how to DJ, and when Ken moved to L.A. to work for a producer, Scott took over his job DJ'ing at the local club. Scott would follow Ken out to L.A., and they formed The Crystal Method in 1993. Ken Jordan and Scott Kirkland bought a house together, in Glendale, California, which had a small underground shelter beneath the front lawn. Originally intending to turn the shelter into a studio, it proved to be an unrealistic idea and the duo set up a studio in their house. They named their studio The Bomb Shelter.

After The Bomb Shelter was built, a tape of The Crystal Method's music found its way to a British DJ named Justin King. King was interested in starting a record label that would showcase American electronic dance acts. King teamed up with Scottish transplant Stephen Melrose to form the record label City of Angels. The first official release from the City of Angels label was The Crystal Method's "Now is the Time". The Crystal Method were signed to Outpost Recordings in 1996.

''Vegas'' (1996–1998)

After the band signed with Outpost, they began working on their debut album. The group's second (and last) single on City of Angels was "Keep Hope Alive". Their next release was on the ''Mortal Kombat: More Kombat'' soundtrack, "Come2gether".

On September 8, 1997, The Crystal Method released their best-selling album, ''Vegas''. ''Vegas'' peaked at number 92 on the Billboard 200. It was certified gold by the RIAA in 1998, then platinum in 2007.

Five of the album's ten tracks were released as singles: "Trip Like I Do", "Busy Child", "High Roller", "Comin' Back", and "Keep Hope Alive".

''Tweekend'' (1999–2002)

In 1999, the band went into the studio to record their next studio album, ''Tweekend'', which featured more guest artists than ''Vegas'' had. The album was released in July 2001, and peaked at number 32 on the Billboard 200, which is still the group's highest album chart position.

Featured guests from the album include Rage Against the Machine guitarist Tom Morello, Stone Temple Pilots vocalist Scott Weiland, and others, like Doug Grean, DJ Swamp, Ryan "Ryu" Maginn, and Julie Gallios. Four singles were released from ''Tweekend'': "Wild, Sweet and Cool", "Murder", "Blowout", "Name of the Game".

''Community Service''

Jordan and Kirkland used to have a radio show called "Community Service" which aired Friday nights on radio station Indie 103.1, in California. They played electronic music and hosted guests, like Death in Vegas and UNKLE.

A year after the release of ''Tweekend'', The Crystal Method released a continuous mix album based on their radio show, titled ''Community Service''. The album does not feature any new studio material from The Crystal Method, but is composed of remixes of bands like P.O.D., Rage Against the Machine, and Garbage, plus remixes of songs from ''Tweekend''. Their remix of P.O.D.'s "Boom" from this album, also appeared in the video game Amplitude.

''Community Service'' peaked at number 160 on the Billboard 200, number five on the Top Electronic Albums chart, and number 15 on the Top Independent Albums chart.

''Legion of Boom'' (2003–2005)

After the release of ''Community Service'', The Crystal Method went back into the studio to record their third album, ''Legion of Boom''. During the recording, they used the house as their recording studio instead of The Bomb Shelter.

In December 2003, the single "Born Too Slow", with vocals from John Garcia and guitar by Wes Borland was released. ''Legion of Boom'' was released on January 13, 2004, and peaked at number 36 on the Billboard 200. It sold over 25,000 copies in its first week.

The other single released from ''Legion of Boom'', "Starting Over", featured vocals from Rahzel from The Roots. No other singles were released but other songs, including "Weapons of Mass Distortion", "Bound Too Long" and "Realizer", appeared in various movies and TV shows. "I Know It's You" appeared in the trailer for the film ''Resident Evil: Extinction'', and includes vocals by the movie's star, Milla Jovovich.

In 2005, the album was nominated for the Best Electronic/Dance Album Grammy, the first year that category existed. It lost to ''Kish Kash'' by Basement Jaxx.

It is also around this time that Jordan and Kirkland formed their own record label, called Tiny e Recordings.

''Community Service II''

On April 5, 2005, The Crystal Method released their sequel to ''Community Service'', called ''Community Service II'', another continuous mix of electronica songs and remixes of music by artists including The Doors, Unkle, New Order and Smashing Pumpkins. The album peaked at number 31 on the Top Independent Albums chart and number 8 on the Top Electronic albums chart.

A 5-track EP, ''Community Service II Exclusives'', was also released through the iTunes Store. It included one new track, "Badass", and full versions of four tracks from ''Community Service II''. It was removed from the iTunes store not long after it was released.

''Drive'', ''London'', and ''Vegas'' re-release (2006–2008)

The group composed and performed the score for the film ''London'', which was released in February 2006. The soundtrack album included excerpts from the score, two Crystal Method vocal tracks—"Smoked" and "Glass Breaker", which were also released as a single—and songs by artists like Evil Nine, The Out Crowd, and The Perishers.

Shortly after the release of the ''London'' soundtrack, The Crystal Method was approached by Nike to take part in a series of music releases specifically designed to be listened to while running. The group's contribution, ''Drive: Nike + Original Run''—the first in the series—was initially released digitally, in June 2006, with the physical release following a year later. ''Drive'' peaked at number 23 on the Top Electronic Albums chart. The album, a 45 minute continuous mix, starts off slow, increases in tempo, and slows at the end, following the arc of a typical distance run.

In 2007, ten years after its original release, the group's debut album, ''Vegas'' was certified platinum by the RIAA. One month later, a special edition of the album was released, with a second disc including remixes and video.

In late 2008, the group remixed their song "Now Is the Time". Where the original version featured samples of Jesse Jackson, this "Vote '08 Remix" used samples of Barack Obama, marking the presidential election.

''Divided by Night'' (2009–present)

Following the release of ''Legion of Boom'', The Crystal Method began construction of a new, full-sized recording studio in Los Angeles—Crystalwerks. When it was finished, they began work on their next album, ''Divided by Night''.

On April 14, 2009, The Crystal Method released the digital single "Drown in the Now". A second single, "Black Rainbows", was released via Beatport two weeks later.

The ''Divided by Night'' tour started in Boston on May 6, and the album was released the following week. It peaked at number 38 on the Billboard 200, number two on the Top Electronic Albums chart, and number four on the Top Independent Albums chart, and also granted the duo another Grammy nomination. The album features guest artists including Peter Hook (of New Order), Matisyahu, Meiko, Justin Warfield, Emily Haines (of Metric), and Jason Lytle.

''X Games 3D: The Movie'', released in August 2009, included a number of Crystal Method songs and remixes, including "Drown in the Now" and "Now Is the Time".

Instruments

The Crystal Method use a wide array of equipment, with the Clavia Nord Lead being most closely associated with their style and sound. It was the primary source of sound for their first album ''Vegas''.

Discography

Studio albums

''Vegas'' (1997)

''Tweekend'' (2001)

''Legion of Boom'' (2004)

''Divided by Night'' (2009)

References

External links

Category:American electronic music groups Category:American techno music groups Category:Club DJs Category:Remixers Category:Musical groups from Los Angeles, California Category:Ableton Live users Category:Breakbeat musicians Category:Electronic music duos

de:The Crystal Method es:The Crystal Method fr:The Crystal Method it:The Crystal Method nl:The Crystal Method pl:The Crystal Method pt:The Crystal Method ru:The Crystal Method uk:The Crystal Method

Name	Heinrich Rudolf Hertz
Birth date	February 22, 1857
Birth place	Hamburg, Germany
Residence	Germany
Nationality	German
Death date	January 01, 1894
Death place	Bonn, Germany
Field	Physics Electronic Engineering
Work institutions	University of Kiel University of Karlsruhe University of Bonn
Alma mater	University of Munich University of Berlin
Doctoral advisor	Hermann von Helmholtz
Doctoral students
Known for	Electromagnetic radiation Photoelectric effect
Signature	Autograph of Heinrich Hertz.png }}

Heinrich Rudolf Hertz (February 22, 1857 – January 1, 1894) was a German physicist who clarified and expanded the electromagnetic theory of light that had been put forth by Maxwell. He was the first to satisfactorily demonstrate the existence of electromagnetic waves by building an apparatus to produce and detect VHF or UHF radio waves.

Biography

Early years

Hertz waz born in Hamburg, Germany, into a prosperous and cultured Hanseatic family. His father, Gustav Ferdinand Hertz, was a writer and later a senator. His mother was the former Anna Elisabeth Pfefferkorn. He had three younger brothers and one younger sister.

While studying at the Gelehrtenschule des Johanneums in Hamburg, he showed an aptitude for sciences as well as languages, learning Arabic and Sanskrit. He studied sciences and engineering in the German cities of Dresden, Munich and Berlin, where he studied under Gustav R. Kirchhoff and Hermann von Helmholtz.

In 1880, Hertz obtained his PhD from the University of Berlin; and remained for post-doctoral study under Hermann von Helmholtz.

In 1883, Hertz took a post as a lecturer in theoretical physics at the University of Kiel.

In 1885, Hertz became a full professor at the University of Karlsruhe where he discovered electromagnetic waves.

The most dramatic prediction of Maxwell's theory of electromagnetism, published in 1865, was the existence of electromagnetic waves moving at the speed of light, and the conclusion that light itself was just such a wave. This challenged experimentalists to generate and detect electromagnetic radiation using some form of electrical apparatus.

The first clearly successful attempt was made by Heinrich Hertz in 1886. For his radio wave transmitter he used a high voltage induction coil, a condenser (capacitor, Leyden jar) and a spark gap - whose poles on either side are formed by spheres of 2 cm radius - to cause a spark discharge between the spark gap’s poles oscillating at a frequency determined by the values of the capacitor and the induction coil.

To prove there really was radiation emitted, it had to be detected. Hertz used a piece of copper wire, 1 mm thick, bent into a circle of a diameter of 7.5 cm, with a small brass sphere on one end, and the other end of the wire was pointed, with the point near the sphere. He added a screw mechanism so that the point could be moved very close to the sphere in a controlled fashion. This "receiver" was designed so that current oscillating back and forth in the wire would have a natural period close to that of the "transmitter" described above. The presence of oscillating charge in the receiver would be signaled by sparks across the (tiny) gap between the point and the sphere (typically, this gap was hundredths of a millimeter).

In more advanced experiments, Hertz measured the velocity of electromagnetic radiation and found it to be the same as the light’s velocity. He also showed that the nature of radio waves’ reflection and refraction was the same as those of light, and established beyond any doubt that light is a form of electromagnetic radiation obeying the Maxwell equations.

Hertz's experiments would soon trigger the invention of the wireless telegraph, radio, and later television. In recognition of his work, the unit of frequency - one cycle per second - is named the "hertz".

Meteorology

He always had a deep interest in meteorology probably derived from his contacts with Wilhelm von Bezold (who was Hertz's professor in a laboratory course at the Munich Polytechnic in the summer of 1878). Hertz, however, did not contribute much to the field himself except some early articles as an assistant to Helmholtz in Berlin, including research on the evaporation of liquids, a new kind of hygrometer, and a graphical means of determining the properties of moist air when subjected to adiabatic changes.

Contact mechanics

In 1886–1889, Hertz published two articles on what was to become known as the field of contact mechanics. Hertz is well known for his contributions to the field of electrodynamics (''see below''); however, most papers that look into the fundamental nature of contact cite his two papers as a source for some important ideas. Joseph Valentin Boussinesq published some critically important observations on Hertz's work, nevertheless establishing this work on contact mechanics to be of immense importance. His work basically summarises how two axi-symmetric objects placed in contact will behave under loading, he obtained results based upon the classical theory of elasticity and continuum mechanics. The most significant failure of his theory was the neglect of any nature of adhesion between the two solids, which proves to be important as the materials composing the solids start to assume high elasticity. It was natural to neglect adhesion in that age as there were no experimental methods of testing for it.

To develop his theory Hertz used his observation of elliptical Newton's rings formed upon placing a glass sphere upon a lens as the basis of assuming that the pressure exerted by the sphere follows an elliptical distribution. He used the formation of Newton's rings again while validating his theory with experiments in calculating the displacement which the sphere has into the lens. K. L. Johnson, K. Kendall and A. D. Roberts (JKR) used this theory as a basis while calculating the theoretical displacement or ''indentation depth'' in the presence of adhesion in their landmark article "Surface energy and contact of elastic solids" published in 1971 in the Proceedings of the Royal Society (A324, 1558, 301-313). Hertz's theory is recovered from their formulation if the adhesion of the materials is assumed to be zero. Similar to this theory, however using different assumptions, B. V. Derjaguin, V. M. Muller and Y. P. Toporov published another theory in 1975, which came to be known as the DMT theory in the research community, which also recovered Hertz's formulations under the assumption of zero adhesion. This DMT theory proved to be rather premature and needed several revisions before it came to be accepted as another material contact theory in addition to the JKR theory. Both the DMT and the JKR theories form the basis of contact mechanics upon which all transition contact models are based and used in material parameter prediction in Nanoindentation and Atomic Force Microscopy. So Hertz's research from his days as a lecturer, preceding his great work on electromagnetism, which he himself considered with his characteristic soberness to be trivial, has come down to the age of nanotechnology.

Electromagnetic research

In 1886, Hertz developed the Hertz antenna receiver. This is a set of terminals that is not electrically grounded for its operation. He also developed a transmitting type of dipole antenna, which was a center-fed driven element for transmitting UHF radio waves. These antennas are the simplest practical antennas from a theoretical point of view.

In 1887, Hertz experimented with radio waves in his laboratory. These actions followed Michelson's 1881 experiment (precursor to the 1887 Michelson-Morley experiment) which did not detect the existence of aether drift, Hertz altered the Maxwell's equations to take this view into account for electromagnetism. Hertz used a Ruhmkorff coil-driven spark gap and one meter wire pair as a radiator. Capacity spheres were present at the ends for circuit resonance adjustments. His receiver, a precursor to the dipole antenna, was a simple half-wave dipole antenna for shortwaves. Hertz published his work in a book titled: ''Electric waves: being researches on the propagation of electric action with finite velocity through space''.

Through experimentation, he proved that transverse free space electromagnetic waves can travel over some distance. This had been predicted by James Clerk Maxwell and Michael Faraday. With his apparatus configuration, the electric and magnetic fields would radiate away from the wires as transverse waves. Hertz had positioned the oscillator about 12 meters from a zinc reflecting plate to produce standing waves. Each wave was about 4 meters. Using the ring detector, he recorded how the magnitude and wave's component direction vary. Hertz measured Maxwell's waves and demonstrated that the velocity of radio waves was equal to the velocity of light. The electric field intensity and polarity was also measured by Hertz. (Hertz, 1887, 1888).

The Hertzian cone was first described by Hertz as a type of wave-front propagation through various media. His experiments expanded the field of electromagnetic transmission and his apparatus was developed further by others in the radio. Hertz also found that radio waves could be transmitted through different types of materials, and were reflected by others, leading in the distant future to radar.

Hertz helped establish the photoelectric effect (which was later explained by Albert Einstein) when he noticed that a charged object loses its charge more readily when illuminated by ultraviolet light. In 1887, he made observations of the photoelectric effect and of the production and reception of electromagnetic (EM) waves, published in the journal Annalen der Physik. His receiver consisted of a coil with a spark gap, whereupon a spark would be seen upon detection of EM waves. He placed the apparatus in a darkened box to see the spark better. He observed that the maximum spark length was reduced when in the box. A glass panel placed between the source of EM waves and the receiver absorbed ultraviolet radiation that assisted the electrons in jumping across the gap. When removed, the spark length would increase. He observed no decrease in spark length when he substituted quartz for glass, as quartz does not absorb UV radiation. Hertz concluded his months of investigation and reported the results obtained. He did not further pursue investigation of this effect, nor did he make any attempt at explaining how the observed phenomenon was brought about.

Hertz did not realize the practical importance of his experiments. He stated that, : "''It's of no use whatsoever''[...]'' this is just an experiment that proves Maestro Maxwell was right - we just have these mysterious electromagnetic waves that we cannot see with the naked eye. But they are there.''" Asked about the ramifications of his discoveries, Hertz replied, : "''Nothing, I guess''." His discoveries would later be more fully understood by others and be part of the new "wireless age". In bulk, Hertz' experiments explain reflection, refraction, polarization, interference, and velocity of electric waves.

In 1892, Hertz began experimenting and demonstrated that cathode rays could penetrate very thin metal foil (such as aluminium). Philipp Lenard, a student of Heinrich Hertz, further researched this "ray effect". He developed a version of the cathode tube and studied the penetration by X-rays of various materials. Philipp Lenard, though, did not realize that he was producing X-rays. Hermann von Helmholtz formulated mathematical equations for X-rays. He postulated a dispersion theory before Röntgen made his discovery and announcement. It was formed on the basis of the electromagnetic theory of light (''Wiedmann's Annalen'', Vol. XLVIII). However, he did not work with actual X-rays.

Death at age 36

In 1892, an infection was diagnosed (after a bout of severe migraines) and Hertz underwent some operations to correct the illness. He died of Wegener's granulomatosis at the age of 36 in Bonn, Germany in 1894, and was buried in Ohlsdorf, Hamburg at the Jewish cemetery.

Hertz's wife, Elizabeth Hertz (maiden name: Elizabeth Doll), did not remarry. Heinrich Hertz left two daughters, Joanna and Mathilde. Subsequently, all three women left Germany in the 1930s to England, after the rise of Adolf Hitler. Charles Susskind interviewed Mathilde Hertz in the 1960s and he later published a book on Heinrich Hertz. Heinrich Hertz's daughters never married and he does not have any descendants, according to the book by Susskind.

Legacy and honors

His nephew Gustav Ludwig Hertz was a Nobel Prize winner, and Gustav's son Carl Hellmuth Hertz invented medical ultrasonography.

The SI unit ''hertz'' (Hz) was established in his honor by the IEC in 1930 for frequency, a measurement of the number of times that a repeated event occurs per second (also called "cycles per sec" (cps)). It was adopted by the CGPM (Conférence générale des poids et mesures) in 1964.

In 1969 (East Germany), there was cast a Heinrich Hertz memorial medal. The IEEE Heinrich Hertz Medal, established in 1987, is "''for outstanding achievements in Hertzian waves ''[...]'' presented annually to an individual for achievements which are theoretical or experimental in nature''".

A crater that lies on the far side of the Moon, just behind the eastern limb, is named in his honor. The Hertz market for radioelectronics products in Nizhny Novgorod, Russia, is named after him. The Heinrich-Hertz-Turm radio telecommunication tower in Hamburg is named after the city's famous son.

Hertz is honored by Japan with a membership in the Order of the Sacred Treasure, which has multiple layers of honor for prominent people, including scientists.

Heinrich Hertz was honored by a number of countries around the world in their postage issues and in Post World War II times has appeared on various German stamp issues as well.

Nazi revisionism

Although Hertz would not have considered himself Jewish, his "Jewish" portrait was removed by the Nazis from its prominent position of honor in Hamburg's City Hall (''Rathaus'') because of his partly "Jewish ancestry." Hertz was a Lutheran; and although his father’s family had been Jewish, his father had converted to Catholicism before marrying. The painting has since been returned to public display.

See also

;People

Berend Wilhelm Feddersen

Hans Christian Ørsted

David Edward Hughes

Reginald Aubrey Fessenden

Guglielmo Marconi

Nikola Tesla

Wilhelm Röntgen

;Lists and histories

Electromagnetism timeline

Timeline of mechanics and physics

List of physicists

Radio history

Wireless telegraphy

List of people on stamps of Germany

List of physics topics

;Electromagnetic radiation

Microwave

;Other

German inventors and discoverers

Notes

References

Hertz, H.R. "Ueber sehr schnelle electrische Schwingungen", ''Annalen der Physik'', vol. 267, no. 7, p. 421-448, May 1887. (WILEY InterScience)

Hertz, H.R. "Ueber einen Einfluss des ultravioletten Lichtes auf die electrische Entladung", ''Annalen der Physik'', vol. 267, no. 8, p. 983-1000, June, 1887. (WILEY InterScience)

Hertz, H.R. "Ueber die Einwirkung einer geradlinigen electrischen Schwingung auf eine benachbarte Strombahn", ''Annalen der Physik'', vol. 270, no. 5, p. 155-170, March, 1888. (WILEY InterScience)

Hertz, H.R. "Ueber die Ausbreitungsgeschwindigkeit der electrodynamischen Wirkungen", ''Annalen der Physik'', vol. 270, no. 7, p. 551-569, May, 1888. (WILEY InterScience)

Hertz, Heinrich Rudolph. (1893). ''Electric waves: being researches on the propagation of electric action with finite velocity through space'' (translated by David Evans Jones). Ithica, New York: Cornell University Library. 10-ISBN 1-429-74036-1; 13-ISBN 978-1-429-74036-4

IEEE (Institute of Electrical and Electronics Engineers) Global History Network, IEEE History Center: "Heinrich Hertz" (retrieved 27 Jan 2007)

Jenkins, John D. "The Discovery of Radio Waves - 1888; Heinrich Rudolf Hertz (1847-1894)" (retrieved 27 Jan 2008)

Koertge, Noretta. (2007). ''Dictionary of Scientific Biography.'' New York: Thomson-Gale. 10-ISBN 0-684-31320-0; 13-ISBN 978-0-684-31320-7

Naughton, Russell. "Heinrich Rudolph (alt: Rudolf) Hertz, Dr : 1857 - 1894" (retrieved 27 Jan 2008)

Roberge, Pierre R. "Heinrich Rudolph Hertz, 1857-1894" (retrieved 27 Jan 2008)

Robertson, Struan. "Buildings Integral to the Former Life and/or Persecution of Jews in Hamburg" (retrieved 27 Jan 2008)

Robertson, Struan. "Heinrich Hertz, 1857-1894" (retrieved 27 Jan 2007)

Further reading

Appleyard, Rollo. (1930). ''Pioneers of Electrical Communication''". London: Macmillan and Company. [reprinted by Ayer Company Publishers, Manchester, New Hampshire: 10-ISBN 0836-90156-8; 13-ISBN 978-0-836-90156-6 (cloth)]

Baird, Davis, R.I.G. Hughes, and Alfred Nordmann, eds. (1998). 'Heinrich Hertz: Classical Physicist, Modern Philosopher.'' New York: Springer-Verlag. 10-ISBN 0-792-34653-X; 13-ISBN 978-0-792-34653-1

Bodanis, David. (2006). ''Electric Universe: How Electricity Switched on the Modern World.'' New York: Three Rivers Press. 10-ISBN 0-307-33598-4; 13-ISBN 978-0-307-33598-2

Buchwald, Jed Z. (1994). ''The Creation of Scientific Effects : Heinrich Hertz and Electric Waves.'' Chicago : University of Chicago Press. 10-ISBN 0-226-07887-6; 13-ISBN 978-0-226-07887-8 (cloth) 10-ISBN 0-226-07888-4; 13-ISBN 978-0-226-07888-5 (paper)

Bryant, John H. (1988). ''Heinrich Hertz, the Beginning of Microwaves: Discovery of Electromagnetic Waves and Opening of the Electromagnetic Spectrum by Heinrich Hertz in the Years 1886-1892.'' New York : IEEE (Institute of Electrical and Electronics Engineers). 10-ISBN 0-879-42710-8; 13-ISBN 978-0-879-42710-8

Heinrich Hertz and his Successors.''">Lodge, Oliver Joseph. (1900). ''Signalling Across Space without Wires by Electric Waves: Being a Description of the work of Heinrich Hertz and his Successors.'' [reprinted by Arno Press, New York, 1974. 10-ISBN 0-405-06051-3

Maugis, Daniel. (2000). ''Contact, Adhesion and Rupture of Elastic Solids.'' New York: Springer-Verlag. 10-ISBN 3-540-66113-1; 13-ISBN 978-3-54066113-9]

Susskind, Charles. (1995).''Heinrich Hertz :a Short Life.'' San Francisco: San Francisco Press. 10-ISBN 0-911-30274-3; 13-ISBN 978-0-911-30274-5

External links

Hertzian radiation - better known as radio waves: what it is and how it happens

''Encyclopædia Britannica'' (1911): Hertz biography

Category:1857 births Category:1894 deaths Category:German physicists Category:German philosophers Category:History of telecommunications Category:German-language philosophers Category:German inventors Category:People from Hamburg Category:Technical University Munich alumni Category:Humboldt University of Berlin alumni Category:University of Bonn faculty Category:Karlsruhe Institute of Technology faculty Category:University of Kiel faculty Category:Radio pioneers

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name	Kevin Farley
birth date	June 08, 1965
birthname	Kevin Peter Farley
birth place	Madison, Wisconsin, U.S.
occupation	Actor
yearsactive	1995–present }}

Kevin Peter Farley (born June 8, 1965) is an American actor, production designer, singer, dancer, occasional composer and aspiring stand-up comic.

Early life

Farley was born in Madison, Wisconsin, the son of Mary Anne (née Crosby), a homemaker, and Thomas Farley, who owned an oil company, Farley Oil. He was raised in an Irish Catholic family. He is the younger brother of late comedian and actor Chris Farley and older brother of actor John P. Farley.

Career

Farley is best known for portraying "Doug Linus" in the fictional boy band 2ge+her. The Farley brothers do routines together and receive roles from many of Chris's ''Saturday Night Live'' castmates, such as David Spade and Adam Sandler, appearing in ''The Waterboy'' and ''Dirty Work''.

Farley appeared on the HBO series, ''Curb Your Enthusiasm'' as an exterminator in the episode, "The Rat Dog." Farley was also in a Dairy Queen commercial advertising the Kit-Kat Blizzard, commercials for Hertz Rent-A-Car, and portrayed Felix the limo driver on Disney's ''That's So Raven''. He also starred in the parody movie ''An American Carol'' in 2008. Farley appeared on ''The View'' (September 30, 2008) to promote the movie.

In 2007, Farley was featured in the web serial, ''Two Guys Drinking at a Bar''.

Farley appeared at the 2008 Republican National Convention, and during an interview with 97.1 FM Talk's Jamie Allman he identified his politics as mostly conservative.

Farley appeared as the kidnapped beer truck driver in the music video for "This Afternoon" by Nickelback.

In May 2010, Farley appeared as a guest on Tom Green's House Tonight where he performed a section of his new standup routine.

References

External links

The Farley brothers' official site.

Category:1965 births Category:American composers Category:American film actors Category:American people of Irish descent Category:Living people Category:Marquette University alumni Category:People from Madison, Wisconsin Category:Actors from Wisconsin

de:Kevin P. Farley fr:Kevin P. Farley it:Kevin Farley sv:Kevin P. Farley