who was the first scientist who produced electromagnetic waves in a laboratory
Heinrich Rudolf Hertz
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by his life's work, on its home page. Heinrich Hertz Heinrich Rudolf Hertz (; ; 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 frequencycycle per secondwas named the "hertz" in his honor. Heinrich 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
Heinrich Hertz
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it was written off as electromagnetic induction at the time. The discovery of electromagnetic waves, including radio waves, by Heinrich Rudolf Hertz in the 1880s came about after over a half century theoretical development on the connection between electricity and magnetism starting in the early 1800s and culminated in a theory of electromagnetism developed by James Clerk Maxwell by 1873, which Hertz finally proved. The development of radio waves into a communication medium did not follow immediately afterwards. After their discovery Hertz considered them of little practical value and other experimenters who explored the physical properties of the new phenomenon,
Invention of radio
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could propagate through free space. It is likely that the first intentional transmission of a signal by means of electromagnetic waves was performed in an experiment by David Edward Hughes around 1880, although this was considered to be induction at the time. In 1888 Heinrich Rudolf Hertz was able to conclusively prove transmitted airborne electromagnetic waves in an experiment confirming Maxwell's theory of electromagnetism. After the discovery of these "Hertzian waves" (it would take almost 20 years for the term "radio" to be universally adopted for this type of electromagnetic radiation) many scientists and inventors experimented with wireless transmission, some
History of radio
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Heinrich Hertz Heinrich Rudolf Hertz (; ; 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 frequencycycle per secondwas named the "hertz" in his honor. Heinrich 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
Heinrich Hertz
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by his life's work, on its home page. Heinrich Hertz Heinrich Rudolf Hertz (; ; 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 frequencycycle per secondwas named the "hertz" in his honor. Heinrich 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
Heinrich Hertz
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light and similarities in electrical and magnetic observations. His mathematical theory, now called Maxwell's equations, described light waves and radio waves as waves of electromagnetism that travel in space, radiated by a charged particle as it undergoes acceleration. In 1887, Heinrich Hertz demonstrated the reality of Maxwell's electromagnetic waves by experimentally generating radio waves in his laboratory, showing that they exhibited the same wave properties as light: standing waves, refraction, diffraction, and polarization. Radio waves, originally called "Hertzian waves", were first used for communication in the mid 1890s by Guglielmo Marconi, who developed the first practical radio transmitters and receivers.
Radio wave
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in 1926 for a thesis on aspects of electromagnetic waves that she wrote in German. Taylor was awarded a Yarrow Research Fellowship which enabled her to remain at Göttingen and continue her work on electromagnetic waves with Professor Richard Courant. In 1929 Taylor returned to the UK and took up a post as Scientific Officer at the Radio Research Station in Slough, Berkshire (part of the UK Department of Scientific and Industrial Research and the UK National Physics Laboratory, now the National Physical Laboratory). Here she continued to carry out research into the theory of electromagnetic waves, specialising in the
Mary Taylor Slow
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Heinrich Hertz Medal (Gold Medal and Monetary Award, IEEE highest recognition for electromagnetic waves), (He was the first recipient, 1989) Microwave Career Award from the IEEE Microwave Theory and Techniques Society in 1985 Son of Samuel and Rebecca M.(Feiner); Married Muriel Spanier, June 30, 1946; children – Andrew, Karen (Levy). Nathan Marcuvitz Nathan Marcuvitz (born December 29, 1913 in Brooklyn, New York, d. February 14, 2010 in Naples, FL), was an American electrical engineer, physicist, and educator who worked in the fields of microwave and electromagnetic theory. He was head of the experimental group of the Radiation Laboratory (MIT). He
Nathan Marcuvitz
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on modelling and applications of thin composite layers with engineered electromagnetic properties (metasurfaces), in particular, developing approaches to full control of reflected and transmitted waves. Sergei Tretyakov (scientist) Sergei Tretyakov () (born in 1956) is a Russian-Finnish scientist, focused in electromagnetic field theory, complex media electromagnetics and microwave engineering. He is currently a professor at Department of Electronics and Nanoengineering, Aalto University (former Helsinki University of Technology), Finland. His main research area in recent years is metamaterials and metasurfaces from fundamentals to applications. He was the president of the European Virtual Institute for Artificial Electromagnetic Materials and Metamaterials (”Metamorphose VI”)
Sergei Tretyakov (scientist)
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Nathan Marcuvitz Nathan Marcuvitz (born December 29, 1913 in Brooklyn, New York, d. February 14, 2010 in Naples, FL), was an American electrical engineer, physicist, and educator who worked in the fields of microwave and electromagnetic theory. He was head of the experimental group of the Radiation Laboratory (MIT). He was a member of the National Academy of Engineering. He had a PhD in electrical engineering from Polytechnic Institute of Brooklyn. "Dr. Nathan Marcuvitz stands out clearly as the leading figure in the field of electromagnetic waves for the period of at least two decades following World War II. He
Nathan Marcuvitz
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a light wave travels through a medium with a varying refractive index, or when a sound wave travels through a medium with varying acoustic impedance. Diffraction has an impact on the acoustic space. Diffraction occurs with all waves, including sound waves, water waves, and electromagnetic waves such as visible light, X-rays and radio waves. Since physical objects have wave-like properties (significantly at the atomic level, invisibly at macro level), diffraction also occurs with matter and can be studied according to the principles of quantum mechanics. Italian scientist Francesco Maria Grimaldi coined the word "diffraction" and was the first to record
Diffraction
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Extremely high frequency Extremely high frequency (EHF) is the International Telecommunication Union (ITU) designation for the band of radio frequencies in the electromagnetic spectrum from 30 to 300 gigahertz (GHz). It lies between the super high frequency band, and the far infrared band, the lower part of which is also referred to as the terahertz gap. Radio waves in this band have wavelengths from ten to one millimetre, giving it the name millimetre band or millimetre wave, sometimes abbreviated MMW or mmW. Millimetre-length electromagnetic waves were first investigated in the 1890s by Indian scientist Jagadish Chandra Bose. Compared to lower
Extremely high frequency
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effects he was observing were results of Maxwell's predicted electromagnetic waves. Starting in November 1887 with his paper "On Electromagnetic Effects Produced by Electrical Disturbances in Insulators", Hertz would send a series of papers to Helmholtz at the Berlin Academy, including papers in 1888 that showed transverse free space electromagnetic waves traveling at a finite speed over a distance. In the apparatus Hertz used, 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
Heinrich Hertz
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for the electromagnetic field which suggested that waves in the field would travel with a speed that was very close to the known speed of light. Maxwell therefore suggested that visible light (as well as invisible infrared and ultraviolet rays by inference) all consisted of propagating disturbances (or radiation) in the electromagnetic field. Radio waves were first produced deliberately by Heinrich Hertz in 1887, using electrical circuits calculated to produce oscillations at a much lower frequency than that of visible light, following recipes for producing oscillating charges and currents suggested by Maxwell's equations. Hertz also developed ways to detect these
Electromagnetic radiation
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James Clerk Maxwell James Clerk Maxwell (13 June 1831 – 5 November 1879) was a Scottish scientist in the field of mathematical physics. His most notable achievement was to formulate the classical theory of electromagnetic radiation, bringing together for the first time electricity, magnetism, and light as different manifestations of the same phenomenon. Maxwell's equations for electromagnetism have been called the "second great unification in physics" after the first one realised by Isaac Newton. With the publication of "A Dynamical Theory of the Electromagnetic Field" in 1865, Maxwell demonstrated that electric and magnetic fields travel through space as waves moving
James Clerk Maxwell
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a linearly polarized wave, a special case. A wave produced by moving your hand in a circle or an ellipse is a circularly or elliptically polarized wave, two other special cases. Electromagnetic waves behave in this same way. Electromagnetic waves are also two-dimensional transverse waves. Transverse waves are waves that travel perpendicular to the direction of the vibration. Ray theory does not describe phenomena such as interference and diffraction, which require wave theory (involving the phase of the wave). You can think of a ray of light, in optics, as an idealized narrow beam of electromagnetic radiation. Rays are used
Transverse wave
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Walter Dieminger Walter Dieminger, (July 7, 1907 – September 29, 2000) was a German space scientist and director of Germany's Max Planck Institute for Aeronomy from 1955 to 1975. Dieminger's research was focused on the ionosphere. Dieminger studied physics between 1926 and 1935 at the University of Technology Munich. After receiving his Ph.D. for work on electromagnetic waves and the ionosphere with Jonathan Zenneck, he worked at the Deutsche Versuchsanstalt für Luftfahrt (German Experimental Institute for Aviation). With his focus on research of the ionosphere and electromagnetic waves at his new institute, called the Zentralstelle für Funkberatung (Central Counseling Office
Walter Dieminger
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digital receivers, a related problem is DC offset of the signal. This is corrected by a similar feedback system. Radio waves were first identified in German physicist Heinrich Hertz's 1887 series of experiments to prove James Clerk Maxwell's electromagnetic theory. Hertz used spark-excited dipole antennas to generate the waves and micrometer spark gaps attached to dipole and loop antennas to detect them. These primitive devices are more accurately described as radio wave sensors, not "receivers", as they could only detect radio waves within about 100 feet of the transmitter, and were not used for communication but instead as laboratory instruments
Radio receiver
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by Charles Glover Barkla showed that X-rays exhibited phenomena associated with electromagnetic waves, including transverse polarization and spectral lines akin to those observed in the visible wavelengths. Single-slit experiments in the laboratory of Arnold Sommerfeld suggested that X-rays had a wavelength of about 1 angstrom. However, X-rays are composed of photons, and thus are not only waves of electromagnetic radiation but also exhibit particle-like properties. Albert Einstein introduced the photon concept in 1905, but it was not broadly accepted until 1922, when Arthur Compton confirmed it by the scattering of X-rays from electrons. Therefore, these particle-like properties of X-rays, such
X-ray crystallography
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interact with other charged particles, exerting force on them. EM waves carry energy, momentum and angular momentum away from their source particle and can impart those quantities to matter with which they interact. Electromagnetic radiation is associated with those EM waves that are free to propagate themselves ("radiate") without the continuing influence of the moving charges that produced them, because they have achieved sufficient distance from those charges. Thus, EMR is sometimes referred to as the far field. In this language, the near field refers to EM fields near the charges and current that directly produced them specifically, electromagnetic induction
Electromagnetic radiation
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Ireland in the International Amateur Radio Union. Radio in Ireland can be traced back to the 1800s with Professor George Francis Fitzgerald of TCD who in conjunction with Heinrich Hertz clarified and confirmed James Clerk Maxwell's mathematical theories of the electromagnetic field. This work led Fitzgerald to conclude in 1883 that an oscillating electric current would produce electromagnetic waves, which was experimentally confirmed by Heinrich Hertz in 1888 and used in the development of wireless telegraphy. Fitzgerald was the first to suggest a method of producing radio frequency waves which forms the basis for modern radio. An early pioneer of
Irish Radio Transmitters Society
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From this, Maxwell concluded that light was a form of electromagnetic radiation: he first stated this result in 1862 in "On Physical Lines of Force". In 1873, he published "A Treatise on Electricity and Magnetism", which contained a full mathematical description of the behaviour of electric and magnetic fields, still known as Maxwell's equations. Soon after, Heinrich Hertz confirmed Maxwell's theory experimentally by generating and detecting radio waves in the laboratory, and demonstrating that these waves behaved exactly like visible light, exhibiting properties such as reflection, refraction, diffraction, and interference. Maxwell's theory and Hertz's experiments led directly to the development
Light
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Possibility of existence of a backward wave medium, where electromagnetic waves propagate with anti-parallel phase and group velocities, was suggested by several scientists throughout the twentieth century: Arthur Schuster, Horace Lamb, Leonid Mandelstam, Victor Veselago, and others. However, due to the absence of materials with such properties in nature, wide interest to the backward wave media was generated only in the early 2000s, when the team of David R. Smith experimentally demonstrated first negative-index metamaterial. In 2003, Tretyakov and colleagues suggested an alternative way to achieve backward waves by using bianisotropic chiral materials. In this case, it is not required
Sergei Tretyakov (scientist)
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in the field. Analyzing the speed of these theoretical waves, Maxwell realized that they must travel at a speed that was about the known speed of light. This startling coincidence in value led Maxwell to make the inference that light itself is a type of electromagnetic wave. Maxwell's equations predicted an infinite number of frequencies of electromagnetic waves, all traveling at the speed of light. This was the first indication of the existence of the entire electromagnetic spectrum. Maxwell's predicted waves included waves at very low frequencies compared to infrared, which in theory might be created by oscillating charges in
Electromagnetic spectrum
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Edouard Sarasin Edouard Sarasin (20 May 1843 – 22 July 1917) was an independent scientist in Geneva. Born in a wealthy family, he established a private laboratory where he collaborated with other researchers. His studies included those on the properties of waves, resonance, radiowaves, radiation and geophysics. Sarasin came from a family of French descent who had settled in Geneva in the early sixteenth century. Sarasin studied physics at Paris, Heidelberg and Berlin and in 1867 he established a private laboratory on rue de l'Hôtel-de-Ville, and worked with other collaborators including Auguste de la Rive (1801-1873) and his son Lucien
Edouard Sarasin
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Prosper-René Blondlot was a professor of physics at the University of Nancy studying electromagnetic radiation. Blondlot was a respected member of the scientific community: he was one of eight physicists who were corresponding members of the French Academy of Sciences and was awarded the Academy's Gaston Planté prize in 1893 and the LaCaze prize in 1899. His attempts to measure the speed of electromagnetic waves were commended by Thomson and Henri Poincaré. After the discovery of X rays, Blondlot began investigating the nature of X rays, trying to determine whether they behaved as particles or electromagnetic waves. (This was before
N ray
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basic "cloaking device", other related concepts have been proposed in peer reviewed, scientific articles, and are discussed here. Naturally, some of the theories discussed here also employ metamaterials, either electromagnetic or acoustic, although often in a different manner than the original demonstration and its successor, the "broad-band cloak". The first electromagnetic cloaking device was produced in 2006, using gradient-index metamaterials. This has led to the burgeoning field of transformation optics (and now transformation acoustics), where the propagation of waves is precisely manipulated by controlling the behaviour of the material through which the light (sound) is travelling. Waves and the host
Theories of cloaking
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Anderson localization In condensed matter physics, Anderson localization (also known as strong localization) is the absence of diffusion of waves in a "disordered" medium. This phenomenon is named after the American physicist P. W. Anderson, who was the first to suggest that electron localization is possible in a lattice potential, provided that the degree of randomness (disorder) in the lattice is sufficiently large, as can be realized for example in a semiconductor with impurities or defects. Anderson localization is a general wave phenomenon that applies to the transport of electromagnetic waves, acoustic waves, quantum waves, spin waves, etc. This phenomenon
Anderson localization
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metal wires, what is now referred as metasurfaces or two-dimensional metamaterials. During the doctoral studies, Tretyakov worked on ferrite-based anisotropic layered structures under supervision of Prof. M.I. Kontorovich. The first research visit to Helsinki University of Technology profoundly influenced his research interest, shifting it towards a novel and very promising direction of complex electromagnetic materials (now called metamaterials). From this time forth Tretyakov actively works in this research direction with the main contributions listed below. Tretyakov made important contributions to research of bianisotropic media. Together with co-authors, he developed the general theory of electromagnetic waves interactions with bianisotropic materials and
Sergei Tretyakov (scientist)
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about 10 times the size. Infrasound is defined by the American National Standards Institute as "sound at frequencies less than 20 Hz." The Allies of World War I first used infrasound to locate artillery. One of the pioneers in infrasonic research was French scientist Vladimir Gavreau. His interest in infrasonic waves first came about in his laboratory during the 1960s, when he and his laboratory assistants experienced shaking laboratory equipment and pain in the eardrums, but his microphones did not detect audible sound. He concluded it was infrasound caused by a large fan and duct system, and soon got to
Infrasound
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1970s, Adair conducted physiology studies as a fellow at the John B. Pierce Laboratory in New Haven to learn how humans and animals react to heat. This work led her to focus on the controversial area of microwaves and their effect on human health. Experimenting on first on squirrel monkeys and then on human volunteers, she concluded that microwave radiation from microwave ovens, cells phones, and power lines is harmless to humans and animals. In 1996, she joined the U.S. Air Force Research Laboratory at Brooks Air Force Base, Texas as a senior scientist studying electromagnetic radiation effects. Adair was
Eleanor R. Adair
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and low frequency alternating current (AC), but not much was known about frequencies above 20 kHz, what are now called radio frequencies. In 1887, four years previously, Heinrich Hertz had discovered Hertzian waves (radio waves), electromagnetic waves which oscillated at very high frequencies. This attracted much attention, and a number of researchers began experimenting with high frequency currents. Tesla's background was in the new field of alternating current power systems, so he understood transformers and resonance. In 1888 he decided that high frequencies were the most promising field for research, and set up a laboratory at 33 South Fifth Avenue,
History of the Tesla coil
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such as Oliver Lodge and Jagadish Chandra Bose, while transmitting radio waves some distance, did not seem to see any value in developing a communication system based on them. In their experiments they did develop electronic components and methods to improve the transmission and detection of electromagnetic waves. In the mid 1890s, building on techniques physicists were using to study electromagnetic waves, Guglielmo Marconi developed the first apparatus for long distance radio communication. On 23 December 1900, the Canadian inventor Reginald A. Fessenden became the first person to send audio (wireless telephony) by means of electromagnetic waves, successfully transmitting over
Invention of radio
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Laboratory of Electromagnetic Research, which has developed into a world-class center for electro-magnetics, having a huge impact on the world's electromagnetic community and on electromagnetic research and education in the Netherlands. Dr. De Hoop's research interests are in the broad area of wavefield modeling in acoustics, electromagnetics and elastodynamics. His interdisciplinary insights and methods in this field can be found in his seminal Handbook of Radiation and Scattering of Waves (1995), with wavefield reciprocity serving as one of the unifying principles governing direct and inverse scattering problems and wave propagation in complex (anisotropic and dispersive) media. He spent a year
Adrianus de Hoop
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Curran made an even greater contribution to victory, in 1945, than Sam." In early 1944 the Currans were part of a group of British scientists invited to go to the US to take part in the Manhattan Project – the Allied project to develop an atomic bomb. They joined the British Mission at the Berkeley Radiation Laboratory in California, headed by Mark Oliphant, a distinguished Australian scientist that Joan knew from the Cavendish Laboratory. Oliphant also acted as "de facto" deputy to Ernest Lawrence, the director of the Radiation Laboratory. The mission of the laboratory was to develop the electromagnetic
Joan Curran
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Natural and Experimental Philosophy in 1881. Along with Oliver Lodge, Oliver Heaviside and Heinrich Hertz, FitzGerald was a leading figure among the group of "Maxwellians" who revised, extended, clarified, and confirmed James Clerk Maxwell's mathematical theories of the electromagnetic field during the late 1870s and the 1880s. In 1883, following from Maxwell's equations, FitzGerald was the first to suggest a device for producing rapidly oscillating electric currents to generate electromagnetic waves, a phenomenon which was first shown to exist experimentally by the German physicist Heinrich Hertz in 1888. In 1883, he was elected Fellow of the Royal Society. In 1899,
George Francis FitzGerald
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trying to develop a system of communication, some intentionally using these new Hertzian waves, some not. Maxwell's theory showing that light and Hertzian electromagnetic waves were the same phenomenon at different wavelengths led "Maxwellian" scientist such as John Perry, Frederick Thomas Trouton and Alexander Trotter to assume they would be analogous to optical signaling and the Serbian American engineer Nikola Tesla to consider them relatively useless for communication since "light" could not transmit further than line of sight. In 1892 the physicist William Crookes wrote on the possibilities of wireless telegraphy based on Hertzian waves and in 1893 Tesla proposed
History of radio
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out up to the end of the year 1886 and the beginning of 1887. For the first time, electromagnetic radio waves ("Hertzian waves") were intentionally and unequivocally proven to have been transmitted through free space by a spark-gap device, and detected over a short distance. Hertz was able to have some control over the frequencies of his radiated waves by altering the inductance and capacitance of his transmitting and receiving antennas. He focused the electromagnetic waves using a corner reflector and a parabolic reflector, to demonstrate that radio behaved the same as light, as Maxwell's electromagnetic theory had predicted more
Invention of radio
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Varian Associates Varian Associates was one of the first high-tech companies in Silicon Valley. It was founded in 1948 by Russell H. and Sigurd F. Varian, William Webster Hansen, and Edward Ginzton to sell the klystron, the first vacuum tube which could amplify electromagnetic waves at microwave frequencies, and other electromagnetic equipment. Varian Associates split into three companies in 1999: Varian Medical Systems, Varian, Inc. and Varian Semiconductor. On April 20, 1948, the Articles of Incorporation were filed, signed by nine directors: Edward Ginzton, who had worked with the Varian brothers since his days as a doctoral student; William Webster
Varian Associates
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a transverse wave. The wavefront of electromagnetic waves emitted from a point source (such as a light bulb) is a sphere. The position of an electromagnetic wave within the electromagnetic spectrum can be characterized by either its frequency of oscillation or its wavelength. Electromagnetic waves of different frequency are called by different names since they have different sources and effects on matter. In order of increasing frequency and decreasing wavelength these are: radio waves, microwaves, infrared radiation, visible light, ultraviolet radiation, X-rays and gamma rays. Electromagnetic waves are emitted by electrically charged particles undergoing acceleration, and these waves can subsequently
Electromagnetic radiation
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Tor Hagfors Tor Hagfors (18 December 1930 – 17 January 2007) was a Norwegian scientist, radio astronomer, radar expert and a pioneer in the studies of the interactions between electromagnetic waves and plasma. In the early 1960s he was one of a handful of pioneering theorists that independently developed a theory that explained the scattering of radio waves by the free electrons in a plasma and applied the result to the ionosphere. He became founding director of the new EISCAT facilities that were then under construction in 1975, by which time he already been director at most of the other
Tor Hagfors
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the transmission of telegraph messages without connecting wires as used by the electric telegraph. This was not a new idea; numerous investigators and inventors had been exploring wireless telegraph technologies and even building systems using electric conduction, electromagnetic induction and optical (light) signalling for over 50 years, but none had proven technically and commercially successful. A relatively new development came from Heinrich Hertz, who, in 1888, demonstrated that one could produce and detect electromagnetic radiation. At the time, this radiation was commonly called "Hertzian" waves, and is now generally referred to as radio waves. There was a great deal of
Guglielmo Marconi
1987102
physicist Heinrich Hertz published the results of his experiments on electromagnetism, which showed the existence of electromagnetic waves in free space. Subsequently, British physicist Oliver Lodge, who had also been researching electromagnetism, conducted a commemorative lecture in August 1894 (after Hertz's death) on the quasi-optical nature of "Hertzian waves" (radio waves) and demonstrated their similarity to light and vision including reflection and transmission at distances up to 50 metres. Lodge's work was published in book form and caught the attention of scientists in different countries, including Bose in India. The first remarkable aspect of Bose's follow-up microwave research was that
Jagadish Chandra Bose
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the Pacific Northwest Laboratory (later renamed Pacific Northwest National Laboratory) as a computer scientist in 1976. He rose through the ranks from senior scientist, staff scientist, chief scientist, to laboratory fellow. In the 1980s, he was a member of the founding team who conceptualized and developed the core concepts for what is today’s William R. Wiley Environmental and Molecular Sciences Laboratory, a DOE scientific user facility located at PNNL. In the early 1990s, to address the problem of information overload, Thomas headed a team of information technology researchers to develop the SPIRE document Visualization (computer graphics) visualization and analytics system.
Jim Thomas (computer scientist)
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induce a changing electric field and vice versa—the two are linked. These changing fields form electromagnetic waves. Electromagnetic waves differ from mechanical waves in that they do not require a medium to propagate. This means that electromagnetic waves can travel not only through air and solid materials, but also through the vacuum of space. The ""history of metamaterials"" can have a variety starting points depending on the properties of interest. Related early wave studies started in 1904 and progressed through more than half of the first part of the twentieth century. This early research included the relationship of the phase
History of metamaterials
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He also studied circular polarization in quartz with Jacques-Louis Soret from 1875. After Soret's death, Sarasin became director of the Archive of Geneva. He received an honorary doctorate from the Universities of Basel in 1885 and Geneva in 1909. Edouard Sarasin Edouard Sarasin (20 May 1843 – 22 July 1917) was an independent scientist in Geneva. Born in a wealthy family, he established a private laboratory where he collaborated with other researchers. His studies included those on the properties of waves, resonance, radiowaves, radiation and geophysics. Sarasin came from a family of French descent who had settled in Geneva in
Edouard Sarasin
129711
Electromagnetic spectrum The electromagnetic spectrum is the range of frequencies (the spectrum) of electromagnetic radiation and their respective wavelengths and photon energies. The electromagnetic spectrum covers electromagnetic waves with frequencies ranging from below one hertz to above 10 hertz, corresponding to wavelengths from thousands of kilometers down to a fraction of the size of an atomic nucleus. This frequency range is divided into separate bands, and the electromagnetic waves within each frequency band are called by different names; beginning at the low frequency (long wavelength) end of the spectrum these are: radio waves, microwaves, terahertz waves, infrared, visible light, ultraviolet,
Electromagnetic spectrum
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research by exposing herself, animals and humans to microwave levels that made them feel warm or even start to sweat and feel quite uncomfortable. She found no adverse health effects other than heat. Microwaves were first generated in the 1880s and 1890s in some of the earliest radio experiments by physicists who thought of them as a form of "invisible light". James Clerk Maxwell in his 1873 theory of electromagnetism, now called Maxwell's equations, had predicted the existence of electromagnetic waves and proposed that light was composed of these waves. In 1888, German physicist Heinrich Hertz was the first to
Microwave
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of that prediction with Helmholtz student Heinrich Hertz's 1888 detection of electromagnetic radiation, was a major triumph for physical theory and raised the possibility that even more fundamental theories based on the field could soon be developed. Experimental confirmation of Maxwell's theory was provided by Hertz, who generated and detected electric waves in 1886 and verified their properties, at the same time foreshadowing their application in radio, television, and other devices. In 1887, Heinrich Hertz discovered the photoelectric effect. Research on the electromagnetic waves began soon after, with many scientists and inventors conducting experiments on their properties. In the mid
19th century in science
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advancements in all of history was the unification of light, electricity and magnetism through Maxwell's electromagnetic theory. A scientific understanding of electricity was necessary for the development of efficient electric generators, motors and transformers. David Edward Hughes and Heinrich Hertz both demonstrated and confirmed the phenomenon of electromagnetic waves that had been predicted by Maxwell. It was Italian inventor Guglielmo Marconi who successfully commercialized radio at the turn of the century. He founded The Wireless Telegraph & Signal Company in Britain in 1897 and in the same year transmitted Morse code across Salisbury Plain, sent the first ever wireless communication
Second Industrial Revolution
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the incoming aircraft while the "Würzburg" calculated the distance and height. In 1935, Hollmann wrote two books on microwaves, "Physics and Technique of Ultra-short Waves" and "Seeing with Electromagnetic Waves", which were the inspiration for the development of centimetre radar in other countries despite some censorship of their contents. During the war he supervised many research institutes in occupied countries and saved many scientists from being deported to Germany. His home and his laboratory in Berlin were destroyed during the war. After the war he was not allowed to work on microwaves but he turned his attention to a wide
Hans Hollmann
6952421
Medical laboratory scientist A medical laboratory scientist (MLS), also traditionally referred to as a clinical laboratory scientist (CLS), is a healthcare professional who performs chemical, hematological, immunologic, histopathological, cytopathological, microscopic, and bacteriological diagnostic analyses on body fluids such as blood, urine, sputum, stool, cerebrospinal fluid (CSF), peritoneal fluid, pericardial fluid, and synovial fluid, as well as other specimens. Medical laboratory scientists work in clinical laboratories at hospitals, reference labs, biotechnology labs and non-clinical industrial labs. Educational and licensing requirements vary by country due to differing scopes of practice and legislative differences. In Australia, medical laboratory scientists complete a four-year undergraduate
Medical laboratory scientist
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supposedly fills all evacuated or non evacuated spaces. The transmission of light or of radiant heat are allowed by the propagation of electromagnetic waves in the ether. Electromagnetic waves have similar characteristics to television and radio broadcasting waves they only differ in wavelength. All electromagnetic waves travel at the same speed; therefore, shorter wavelengths are associated with high frequencies. Since every body or fluid is submerged in the ether, due to the vibration of the molecules, any body or fluid can potentially initiate an electromagnetic wave. All bodies generate and receive electromagnetic waves at the expense of its stored energy
Radiation properties
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Allan Carswell Allan Ian Carswell, CM, FRSC (born 1933) is an internationally recognized leader in the field of laser radar (lidar) applications since the technology's beginning in the early 1960s. Carswell has been actively engaged in the study of the properties and applications of lasers and coherent optical frequency radiation since 1963. He was a member of the Plasma Physics Laboratory at the RCA Victor Research Laboratories in Montreal, Quebec, Canada, studying electromagnetic waves with ionized gas systems. In 1965 Carswell was appointed Director of the RCA Optical and Microwave Research Laboratory, and led the group there that developed the
Allan Carswell
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Gideon's Sword Gideon's Sword is a novel by Douglas Preston and Lincoln Child. It was released on February 22, 2011 by Grand Central Publishing. The book is the first installment in the Gideon Crew series. The novel was optioned by Bay Films and will be produced by Michael Bay. The story introduces Gideon Crew, a scientist at Los Alamos National Laboratory who is also a former art thief/master-of-disguise. He learns from his mother that his mathematician father—who had developed a flawed encryption—had actually warned his boss about the flaws, only to be murdered. Gideon exacts revenge from his father's murderer.
Gideon's Sword
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headed by Mikhail Aleksandrovich Leontovich at LIPAN (Laboratory of Measuring Instruments of the USSR Academy of Sciences) as today's Russian Research Centre "Kurchatov Institute" was known at the time. He examined tokamaks stability and gave some parameter estimation for Soviet tokamak experiments. He also dealt with shock waves in plasmas and interaction of electromagnetic waves with plasmas. Later, he worked intensively on stellarators. In 1981 he became the successor of Leontovich as head of the Theory Department of Nuclear Fusion at the Kurchatov Institute. Concepts such as the Shafranov shift (1959), the Kruskal-Shafranov stability criterion and limit value and the
Vitaly Shafranov
20613823
to engineer negative permittivity and permeability, instead, one should just ensure proper chiral response of the material. In the extreme case of so-called chiral nihility (when both relative permittivity and permeability are much smaller than the chirality parameter), two eigenwaves represent "forward" and "backward" circularly polarized waves with equal phase velocities. The existence of backward waves in chiral media was independently suggested by John Pendry in 2004. Inspired by the idea of transformation-optics based electromagnetic cloaking, Tretyakov's team developed an alternative realization of the same effect for cylindrical objects. In contrast to the previous designs, Tretyakov's cloaking device exhibits significantly
Sergei Tretyakov (scientist)
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Electromagnetic radiation 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-rays, and gamma rays. Classically, electromagnetic radiation consists of electromagnetic waves, which are synchronized oscillations of electric and magnetic fields that propagate at the speed of light, which, in a vacuum, is commonly denoted "c". In homogeneous, isotropic media, the oscillations of the two fields are perpendicular to each other and perpendicular to the direction of energy and wave propagation, forming
Electromagnetic radiation
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Sir Oliver Lodge. During the absence of Oliver Lodge due to ill health, Barkla would replace him in lectures. In 1899 Barkla was admitted to Trinity College, Cambridge, with an 1851 Research Fellowship from the Royal Commission for the Exhibition of 1851, to work in the Cavendish Laboratory under the physicist J. J. Thomson (discoverer of the electron). During his first two years at Cambridge, Barkla would, under the directions of Thomson, study the velocity of electromagnetic waves along wires of different widths and materials. After a year and a half at Trinity College, Cambridge, his love of music led
Charles Glover Barkla
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doctors, due to the sometimes complex nature of the role. Medical laboratory scientist A medical laboratory scientist (MLS), also traditionally referred to as a clinical laboratory scientist (CLS), is a healthcare professional who performs chemical, hematological, immunologic, histopathological, cytopathological, microscopic, and bacteriological diagnostic analyses on body fluids such as blood, urine, sputum, stool, cerebrospinal fluid (CSF), peritoneal fluid, pericardial fluid, and synovial fluid, as well as other specimens. Medical laboratory scientists work in clinical laboratories at hospitals, reference labs, biotechnology labs and non-clinical industrial labs. Educational and licensing requirements vary by country due to differing scopes of practice and legislative
Medical laboratory scientist
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is scattered by dense and turbulent gases, and thus delayed. The neutrino burst is expected to reach Earth before any electromagnetic waves, including visible light, gamma rays, or radio waves. The exact time delay of the electromagnetic waves' arrivals depends on the velocity of the shock wave and on the thickness of the outer layer of the star. For a Type II supernova, astronomers expect the neutrino flood to be released seconds after the stellar core collapse, while the first electromagnetic signal may emerge hours later, after the explosion shock wave has had time to reach the surface of the
Neutrino
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non-radiative dielectric waveguides and the Goubau line, use both metal walls and dielectric surfaces to confine the wave. During the 1890s theorists did the first analyses of electromagnetic waves in ducts. Around 1893 J. J. Thomson derived the electromagnetic modes inside a cylindrical metal cavity. In 1897 Lord Rayleigh did a definitive analysis of waveguides; he solved the boundary-value problem of electromagnetic waves propagating through both conducting tubes and dielectric rods of arbitrary shape. He showed that the waves could travel without attenuation only in specific normal modes with either the electric field (TE modes) or magnetic field (TM modes),
Waveguide (electromagnetism)
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for the system. Edison did not develop the patent commercially but according to his former assistant Francis Jehl, sold it to Guglielmo Marconi who developed it into radio. Etheric force Etheric force is a term Thomas Edison coined to describe a phenomenon later understood as high frequency electromagnetic waves—effectively, radio. Edison believed it was the mysterious force that some believed pervaded the ether. At the end of 1875, Edison and his assistants were experimenting with the Acoustic Telegraph when they noticed that a rapidly vibrating spark gap produced a spark in an adjacent relay. Subsequent investigation showed that the phenomenon
Etheric force
346508
radars, except when their detection is intended. Radar relies on its own transmissions rather than light from the Sun or the Moon, or from electromagnetic waves emitted by the objects themselves, such as infrared wavelengths (heat). This process of directing artificial radio waves towards objects is called "illumination", although radio waves are invisible to the human eye or optical cameras. If electromagnetic waves travelling through one material meet another material, having a different dielectric constant or diamagnetic constant from the first, the waves will reflect or scatter from the boundary between the materials. This means that a solid object in
Radar
656947
magnetic field. The distribution of telluric current density can be used to detect variations in electrical resistivity of underground structures. Geophysicists can also provide the electric current themselves (see induced polarization and electrical resistivity tomography). Electromagnetic waves occur in the ionosphere and magnetosphere as well as the Earth's outer core. Dawn chorus is believed to be caused by high-energy electrons that get caught in the Van Allen radiation belt. Whistlers are produced by lightning strikes. Hiss may be generated by both. Electromagnetic waves may also be generated by earthquakes (see seismo-electromagnetics). In the highly conductive liquid iron of the outer
Geophysics
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Center in Princeton, New Jersey and scientist at Elcon Laboratory, Inc. in Cambridge, Massachusetts. From 1961 to 1965 Uman was associate professor of electrical engineering at the University of Arizona in Tucson. At Arizona Uman taught and conducted research in electromagnetics and gaseous electronics and became interested in the physics of lightning. From 1965 to 1971 Uman was fellow physicist at Westinghouse Research Labs in Pittsburgh. There he studied the physical and electromagnetic aspects of lightning and long laboratory sparks. In 1971 Uman became a professor in the Department of Electrical and Computer Engineering at the University of Florida in
Martin A. Uman
1294839
Royal Society, have used the Proca equation in an attempt to demonstrate photon mass as a longitudinal electromagnetic component of Maxwell's equations, suggesting that longitudinal electromagnetic waves could exist in a Dirac polarized vacuum. After Heaviside's attempts to generalize Maxwell's equations, Heaviside came to the conclusion that electromagnetic waves were not to be found as longitudinal waves in ""free space"" or homogeneous media. But Maxwell's equations do lead to the appearance of longitudinal waves under some circumstances, for example, in plasma waves or guided waves. Basically distinct from the "free-space" waves, such as those studied by Hertz in his UHF
Longitudinal wave
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radio and satellite communications. Radio waves are a type of electromagnetic radiation with wavelengths in the electromagnetic spectrum longer than infrared light. Like all other electromagnetic waves, they travel at the speed of light. Naturally occurring radio waves are made by lightning, or by astronomical objects. Artificially generated radio waves are used for fixed and mobile radio communication, broadcasting, radar and other navigation systems, satellite communication, computer networks and innumerable other applications. Different frequencies of radio waves have different propagation characteristics in the Earth's atmosphere; long waves may cover a part of the Earth very consistently, shorter waves can reflect
Non-ionizing radiation
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can be used for both transmitting and receiving, even simultaneously, depending on the connected equipment. Once generated, electromagnetic waves travel through space either directly, or have their path altered by reflection, refraction or diffraction. The intensity of the waves diminishes due to geometric dispersion (the inverse-square law); some energy may also be absorbed by the intervening medium in some cases. Noise will generally alter the desired signal; this electromagnetic interference comes from natural sources, as well as from artificial sources such as other transmitters and accidental radiators. Noise is also produced at every step due to the inherent properties of
Radio
174970
the existence of airborne electromagnetic waves led to an explosion of experimentation with this new form of electromagnetic radiation, which was called "Hertzian waves" until around 1910 when the term "radio waves" became current. Within 10 years researchers such as Oliver Lodge, Ferdinand Braun, and Guglielmo Marconi employed radio waves in the first wireless telegraphy radio communication systems, leading to radio broadcasting, and later television. Today radio is an essential technology in global telecommunication networks, and the transmission medium underlying modern wireless devices. In 1892, Hertz began experimenting and demonstrated that cathode rays could penetrate very thin metal foil (such
Heinrich Hertz
4774034
steamships – prevented the British and French Allies from occupying Hangö, Sveaborg, and Saint Petersburg. Despite being greatly outnumbered by the technologically superior Allies, it was the Russian Fleet that introduced into naval warfare such novelties as torpedo mines, invented by Boris Yakobi. Other outstanding inventors who served in the Baltic Fleet were Alexander Stepanovich Popov (who was the first to demonstrate the practical application of electromagnetic (radio) waves), Stepan Makarov (the first to launch torpedoes from a boat), Alexei Krylov (author of the modern ship floodability theory), and Alexander Mozhaiski (co-inventor of aircraft). As early as 1861, the first
Baltic Fleet
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open systems interacting with electromagnetic waves or various kinds of fields. Most famous propellantless methods are the gravity assist maneuver or gravitational slingshot of a spacecraft accelerating at the expense of the momentum of the planet it orbits, through the gravitational field, or beam-powered propulsion using the radiation pressure of electromagnetic waves from a distant source like a laser. More speculative methods have also been proposed, like the Woodward effect, the quantum vacuum plasma thruster or various hypotheses trying to explain the thrust apparently produced by the EmDrive. Because there is no well-defined "center of mass" in curved spacetime, general
Reactionless drive
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three main components: the main ovals, which are bright, narrow (< 1000 km in width) circular features located at approximately 16° from the magnetic poles; the satellite auroral spots, which correspond to the footprints of the magnetic field lines connecting their ionospheres with the ionosphere of Jupiter, and transient polar emissions situated within the main ovals. The auroral emissions were detected in almost all parts of the electromagnetic spectrum from radio waves to X-rays (up to 3 keV). The X-ray monitor of Solwind, designated NRL-608 or XMON, was a collaboration between the Naval Research Laboratory and Los Alamos National Laboratory.
X-ray transient
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discovered electromagnetic emissions stimulated by powerful radio waves in the ionosphere during experiments in August 1981 at the EISCAT facility in Tromsø, Norway. For the first time it was shown that the plasma turbulence excited by powerful radio waves in the ionosphere radiates secondary electromagnetic radiation that can be detected and analysed on the ground. These stimulated electromagnetic emissions (SEE) exhibit a rich spectral structure, particularly near harmonics of the ionospheric electron gyro frequency. The SEE technique is now a useful tool in plasma turbulence research. For his discovery, Thidé was awarded the Edlund Prize of the Royal Swedish Academy
Bo Thidé
5491476
Company, and the results were covered up by STC's chairman Sir Frank Gill to maintain Bell's reputation. An early voice communicating device was invented around 1854 by Antonio Meucci, who called it a "telettrofono". In 1871 Meucci filed a caveat at the US Patent Office. His caveat describes his invention, but does not mention a diaphragm, electromagnet, conversion of sound into electrical waves, conversion of electrical waves into sound, or other essential features of an electromagnetic telephone. The first American demonstration of Meucci's invention took place in Staten Island, New York in 1854. In 1861, a description of it was
Invention of the telephone
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Aleksandr Stoletov Alexander Grigorievich Stoletov (; 10 August 1839 – 27 May 1896) was a Russian physicist, founder of electrical engineering, and professor in Moscow University. He was the brother of general Nikolai Stoletov. Alexander Stoletov defended his doctoral dissertation in 1872 and became professor at Moscow University a year later. After defending his dissertation he became a renowned scientist worldwide. He attended the opening ceremony of the physical laboratory in Cambridge in 1874, and represented Russia at the first World Congress of Electricity in Paris in 1881, where he presented his work on links between electrostatic and electromagnetic values.
Aleksandr Stoletov
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of the new Cavendish Laboratory is known for its inscription from the Book of Psalms in the Bible: "The works of the Lord are great, sought out of all them that have pleasure therein." The department is named to commemorate British chemist and physicist Henry Cavendish for contributions to science and his relative William Cavendish, 7th Duke of Devonshire, who served as chancellor of the university and donated money for the construction of the laboratory. Professor James Clerk Maxwell, the developer of electromagnetic theory, was a founder of the lab and became the first Cavendish Professor of Physics. The Duke
Cavendish Laboratory
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method from damped wave signals produced by earlier "spark gap" type transmitters. Very early radio transmitters used a spark gap to produce radio-frequency oscillations in the transmitting antenna. The signals produced by these spark-gap transmitters consisted of strings of brief pulses of sinusoidal radio frequency oscillations which died out rapidly to zero, called damped waves. The disadvantage of damped waves was that their energy was spread over an extremely wide band of frequencies; they had wide bandwidth. As a result, they produced electromagnetic interference (RFI) that spread over the transmissions of stations at other frequencies. This motivated efforts to produce
Continuous wave
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Vibe Technologies had a Class I recall that was completed in 2012 Other ineffectual EMT therapy devices that have been marketed include: Radionics Radionics (also called electromagnetic therapy (EMT)) is a form of alternative medicine that claims disease can be diagnosed and treated by applying electromagnetic radiation (EMR), such as radio waves, to the body from an electrically powered device. It is similar to magnet therapy which also applies EMR to the body, but using a magnet that generates a static electromagnetic field. The concept behind radionics originated in the early 1900s with Albert Abrams (1864–1924), who became a millionaire
Radionics
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Sea interferometry Sea interferometry, also known as Sea-cliff interferometry, is a form of radio astronomy that uses radio waves reflected off the sea to produce an interference pattern. It is the radio wave analogue to Lloyd's mirror. The technique was invented and exploited in Australia between 1945 and 1948. A radio detecting aerial is placed on top of a cliff, which detects electromagnetic waves coming directly from the source and waves reflected off the water surface. The two sets of waves are then combined to form an interference pattern such as that produced by two separate aerials. The reflected wavefront
Sea interferometry
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Administration compiled a catalogue of more than 50 historical incidents probably associated with rogue waves. In 1826, French scientist and naval officer Captain Jules Dumont d'Urville reported waves as high as in the Indian Ocean with three colleagues as witnesses, yet he was publicly ridiculed by fellow scientist François Arago. In that era it was widely held that no wave could exceed . Author Susan Casey wrote that much of that disbelief came because there were very few people who had seen a rogue wave, and until the advent of steel double-hulled ships of the 20th century "people who encountered
Rogue wave
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soon realized that this could better be done using electromagnetic waves. In 1917, the Army established the Signal Corps Radio Laboratories at Camp Vail, in eastern New Jersey. After the war, this became Fort Vail, then in 1925, it was renamed Fort Monmouth. In 1926, Blair was assigned as the Chief of Research and Engineering. Coupling capabilities in electronics and meteorology, in 1929 the Laboratory developed and launched the first radio-equipped weather balloon. Going into the 1930s, the Great Depression with declining economic conditions led the Signal Corps to consolidate their widespread laboratories to Fort Monmouth. On June 30, 1930,
William R. Blair
15491072
lectures on electromagnetic theory inspired Scaife. After graduation, he began research into the properties of insulating materials under Tropper's direction. Scaife's doctoral research broke new ground in the study of dielectrics. Brendan Scaife was the first scientist to successfully measure the complex permittivity of a number of polar liquids such as eugenol, glycerol and water as a function of pressure up to 12 kbar. This is published in a research note in Proc. Phys. Soc. B, 68 (1955) 790. Up to that time, Chan and Danforth working in Bridgman's laboratory in the USA, had measured essentially the equilibrium relative permittivity
Brendan Scaife
3972679
the ship was sinking. They played a crucial role in maritime rescues such as the 1912 RMS "Titanic" disaster. After World War 1, transmitters based on vacuum tubes were developed, which were cheaper and produced continuous waves which had a greater range, produced less interference, and could also carry audio, making spark transmitters obsolete by 1920. The radio signals produced by spark-gap transmitters are electrically "noisy"; they have a wide bandwidth, creating radio frequency interference (RFI) that can disrupt other radio transmissions. This type of radio emission has been prohibited by international law since 1934. Electromagnetic waves are radiated by
Spark-gap transmitter
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Code-E Code-E is a Japanese anime television series animated by Studio Deen. It is based on an original concept by Ichirō Sakaki and directed by Toshiyuki Katō. The first season consists of twelve episodes and first aired in Japan from July 3, 2007 to September 23, 2007. A second season titled Mission-E aired between July 7, 2008 and September 22, 2008. Chinami Ebihara is a high school student who emits electromagnetic waves when her emotions run wild. The waves affects electronics such as cell phones, televisions, and computers. Her ability forces her family to move from one location to another.
Code-E
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Essam Heggy Essam Heggy ( ) is an Egyptian space scientist. Heggy obtained his Ph.D. in astronomy and planetary science in 2002 with distinguished honors from the Sorbonne University in Paris. His main science interests in space and planetary geophysics covers Mars, the Moon, icy satellites and near-Earth objects. His research involves probing structural, hydrological and volcanic elements in terrestrial and planetary environments using different types of radar imaging and sounding techniques as well as measuring the electromagnetic properties of rocks in the radar frequency range. His research expertise span from laboratory electromagnetic characterization of planetary analog materials, Radar sounding
Essam Heggy
9451890
speed of electromagnetic waves in a low-loss dielectric is given by where The speed of electromagnetic waves in a good conductor is given by where In copper at 60 Hz, formula_23 3.2 m/s. Some sprinters can run more than three times as fast. As a consequence of Snell's Law and the extremely low speed, electromagnetic waves always enter good conductors in a direction that is normal to the surface, regardless of the angle of incidence. This velocity is the speed with which electromagnetic waves penetrate into the conductor and is not the drift velocity of the conduction electrons. In the
Speed of electricity
14977776
from her position as Chief Scientist of the Computational and Information Sciences Directorate at the United States Army Research Laboratory(ARL). Ulery was among the first group of female managers at the US Army Research Laboratory. In these positions, she was also appointed Chair of the US Army Materiel Command Knowledge Management Council, and in 2002 was awarded the Army Knowledge Award for Best Transformation Initiative. She is listed in American Men and Women of Science, Who’s Who of American Women, Who’s Who in the East, Who’s Who in the World, and Who’s Who in America. She was named a Lifetime
Dana Ulery
958486
Radio wave Radio waves are a type of electromagnetic radiation with wavelengths in the electromagnetic spectrum longer than infrared light. Radio waves have frequencies as high as 300 gigahertz (GHz) to as low as 30 hertz (Hz). At 300 GHz, the corresponding wavelength is 1 mm, and at 30 Hz is 10,000 km. Like all other electromagnetic waves, radio waves travel at the speed of light. They are generated by electric charges undergoing acceleration, such as time varying electric currents. Naturally occurring radio waves are emitted by lightning and astronomical objects. Radio waves are generated artificially by transmitters and received
Radio wave
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themselves the task of experimentally demonstrating the truth of the theory. By 1871, he presented the "Remarks on the mathematical classification of physical quantities". In 1887, the German physicist Heinrich Hertz in a series of experiments proved the actual existence of electromagnetic waves, showing that transverse free space electromagnetic waves can travel over some distance as predicted by Maxwell and Faraday. Hertz published his work in a book titled: "Electric waves: being researches on the propagation of electric action with finite velocity through space". The discovery of electromagnetic waves in space led to the development of radio in the closing
History of electromagnetic theory
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magnetic field created by charged particles moving along a medium. For example, radio waves are emitted by electricity moving along a radio transmitter, or even from a satellite. In the case of electromagnetic side-channel attacks, attackers are often looking at electromagnetic radiation emitted by computing devices, which are made up of circuits. Electronic circuits consist of semiconducting materials upon which billions of transistors are placed. When a computer performs computations, such as encryption, electricity running through the transistors create a magnetic field and electromagnetic waves are emitted. Electromagnetic waves can be captured using an induction coil and an analog to
Electromagnetic attack
695586
approach to quantifying autonomous capabilities is based on OODA terminology, as suggested by a 2002 US Air Force Research Laboratory, and used in the table below: Reactive autonomy, such as collective flight, real-time collision avoidance, wall following and corridor centring, relies on telecommunication and situational awareness provided by range sensors: optic flow, lidars (light radars), radars, sonars. Most range sensors analyze electromagnetic radiation, reflected off the environment and coming to the sensor. The cameras (for visual flow) act as simple receivers. Lidars, radars and sonars (with sound mechanical waves) emit and receive waves, measuring the round-trip transit time. UAV cameras
Unmanned aerial vehicle
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electronic or mechanical components up to large earthquakes. Although most progress has been made on mathematical and theoretical solutions, a laboratory metamaterial device for evading sonar has been recently demonstrated. It can be applied to sound wavelengths from 40 to 80 kHz. Waves also apply to bodies of water. A theory has been developed for a cloak that could "hide", or protect, man-made platforms, ships, and natural coastlines from destructive ocean waves, including tsunamis. Theories of cloaking Theories of cloaking discusses various theories based on science and research, for producing an electromagnetic cloaking device. Theories presented employ transformation optics, event
Theories of cloaking
20191923
that the numerical value of this ratio was equal to the speed of electromagnetic waves. Maxwell recognised that the speed of electromagnetic waves (as derived from his equations) was also equal to the speed of light as measured by Fizeau and as previously measured in the 17th century by Ole Roemer. In his 1865 paper, Maxwell stated the immortal words "“…it seems we have strong reason to conclude that light itself (including radiant heat and other radiations if any) is an electromagnetic disturbance in the form of waves propagated …according the electromagnetic laws”". This was stated by the Nobel Laureate
James Clerk Maxwell Foundation
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Pana Wave The Pana-Wave Laboratory () is a Japanese new religious group or "Shinshūkyō". Estimates of membership range from several hundred to 1,200. Pana-Wave is an offshoot of a religious group called Chino-Shoho ("True Law of Chino") based in Shibuya, Tokyo, founded by a woman called Yuko Chino in 1977 and combining elements of Christianity, Buddhism and New Age doctrines. In the mid 1980s, members calling themselves the "scientific faction", and warning of the evils of electromagnetic waves (which the group claimed were causing catastrophic environmental destruction and climate change) built the Pana-Wave Laboratory in Fukui Prefecture in an area
Pana Wave
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built the first experimental spark gap transmitters during his historic experiments to demonstrate the existence of electromagnetic waves predicted by James Clerk Maxwell in 1864, in which he discovered radio waves, See circuit diagram. Hertz's transmitters consisted of a dipole antenna made of a pair of collinear metal rods of various lengths with a spark gap "(S)" between their inner ends and metal balls or plates for capacitance "(C)" attached to the outer ends. The two sides of the antenna were connected to an induction coil (Ruhmkorff coil) "(T)" a common lab power source which produced pulses of high voltage,
Spark-gap transmitter
121403
vary in size, from very long radio waves the size of buildings to very short gamma rays smaller than atom nuclei. Frequency is inversely proportional to wavelength, according to the equation: where "v" is the speed of the wave ("c" in a vacuum, or less in other media), "f" is the frequency and λ is the wavelength. As waves cross boundaries between different media, their speeds change but their frequencies remain constant. Electromagnetic waves in free space must be solutions of Maxwell's electromagnetic wave equation. Two main classes of solutions are known, namely plane waves and spherical waves. The plane
Electromagnetic radiation
467681
as their ionization of gases, caused William Henry Bragg to argue in 1907 that X-rays were "not" electromagnetic radiation. Nevertheless, Bragg's view was not broadly accepted and the observation of X-ray diffraction by Max von Laue in 1912 confirmed for most scientists that X-rays were a form of electromagnetic radiation. Crystals are regular arrays of atoms, and X-rays can be considered waves of electromagnetic radiation. Atoms scatter X-ray waves, primarily through the atoms' electrons. Just as an ocean wave striking a lighthouse produces secondary circular waves emanating from the lighthouse, so an X-ray striking an electron produces secondary spherical waves
X-ray crystallography
7192053
electromagnetic waves propagate along null geodesics of the physical spacetime (as defined by the metric determined from geometrical measurements and timing experiments), while gravitational waves propagate along null geodesics of a "flat background" represented by the metric tensor of Minkowski spacetime. The gravitational potential can be expressed entirely in terms of waves retarded along the background metric, like the Liénard–Wiechert potential in electromagnetic theory. A cosmological constant can be introduced by changing the background metric to a de Sitter or anti-de Sitter metric. This was first suggested by G. Temple in 1923. Temple's suggestions on how to do this were
Whitehead's theory of gravitation
122655
(rather, it is indirectly produced by a sequences of changes in fields radiating out from them in the past). EMR consists of the radiations in the electromagnetic spectrum, including radio waves, microwave, infrared, visible light, ultraviolet light, X-rays, and gamma rays. The many commercial applications of these radiations are discussed in the named and linked articles. A notable application of visible light is that this type of energy from the Sun powers all life on Earth that either makes or uses oxygen. A changing electromagnetic field which is physically close to currents and charges (see near and far field for
Electromagnetic field
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Radio Radio is the technology of using radio waves to carry information, such as sound, by systematically modulating properties of electromagnetic energy waves transmitted through space, such as their amplitude, frequency, phase, or pulse width. When radio waves strike an electrical conductor, the oscillating fields induce an alternating current in the conductor. The information in the waves can be extracted and transformed back into its original form. Radio systems need a transmitter to modulate (change) some property of the energy produced to impress a signal on it, for example using amplitude modulation or angle modulation (which can be frequency modulation
Radio