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Timeline Of Radio
The timeline of radio lists within the history of radio, the technology and events that produced instruments that use radio waves and activities that people undertook. Later, the history is dominated by programming and contents, which is closer to general history. Origins and developments Although development of the first radio wave communication system is attributed to Guglielmo Marconi, his was just the practical application of 80 years of scientific advancement in the field including the predictions of Michael Faraday, the theoretical work of James Clerk Maxwell, and the experimental demonstrations of Heinrich Rudolf Hertz. * 1780–1784: George Adams notices sparks between charged and uncharged conductors when a Leyden jar was discharged nearby. * 1789–1791: Luigi Galvani notices a spark generated nearby causes a convulsion in a frog's leg being touched by a scalpel. Lindell, pp. 258–261 In different experiments, he notices contractions in frogs' legs caused by lightning ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
History Of Radio
The early history of radio is the history of technology that produces and uses radio equipment, radio instruments that use radio waves. Within the timeline of radio, many people contributed theory and inventions in what became radio. Radio development began as "wireless telegraphy". Later radio history increasingly involves matters of broadcasting. Discovery In an 1864 presentation, published in 1865, James Clerk Maxwell proposed theories of electromagnetism, with mathematical proofs, that showed that light and predicted that radio and x-rays were all types of electromagnetic waves propagating through free space. Between 1886 and 1888 Heinrich Rudolf Hertz published the results of experiments wherein he was able to transmit electromagnetic waves (radio waves) through the air, proving Maxwell's electromagnetic theory. [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Electromagnetic Induction
Electromagnetic or magnetic induction is the production of an electromotive force (emf) across an electrical conductor in a changing magnetic field. Michael Faraday is generally credited with the discovery of induction in 1831, and James Clerk Maxwell mathematically described it as Faraday's law of induction. Lenz's law describes the direction of the induced field. Faraday's law was later generalized to become the Maxwell–Faraday equation, one of the four Maxwell equations in his theory of electromagnetism. Electromagnetic induction has found many applications, including electrical components such as inductors and transformers, and devices such as electric motors and generators. History Electromagnetic induction was discovered by Michael Faraday, published in 1831. It was discovered independently by Joseph Henry in 1832. In Faraday's first experimental demonstration (August 29, 1831), he wrapped two wires around opposite sides of an iron ring or "torus" (an arrangement ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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.Wills, Ian. 2009. Edison and science: A curious result. ''Studies in History and Philosophy of Science Part A'' 40 (June):157-166 Subsequent investigation showed that the phenomenon could be made to occur at a distance of several feet without interconnecting cables. Edison, with this small amount of evidence, announced that it was "a true unknown force", since he believed that the spark transmitted electricity without carrying any charge. Edison concluded that this discovery had the potential to cheapen telegraphic communication and to allow transatlantic cables to be la ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Galvanometer
A galvanometer is an electromechanical measuring instrument for electric current. Early galvanometers were uncalibrated, but improved versions, called ammeters, were calibrated and could measure the flow of current more precisely. A galvanometer works by deflecting a pointer in response to an electric current flowing through a coil in a constant magnetic field. Galvanometers can be thought of as a kind of actuator. Galvanometers came from the observation, first noted by Hans Christian Ørsted in 1820, that a magnetic compass's needle deflects when near a wire having electric current. They were the first instruments used to detect and measure small amounts of current. André-Marie Ampère, who gave mathematical expression to Ørsted's discovery, named the instrument after the Italian electricity researcher Luigi Galvani, who in 1791 discovered the principle of the frog galvanoscope – that electric current would make the legs of a dead frog jerk. Galvanometers have bee ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Electroscope
The electroscope is an early scientific instrument used to detect the presence of electric charge on a body. It detects charge by the movement of a test object due to the Coulomb electrostatic force on it. The amount of charge on an object is proportional to its voltage. The accumulation of enough charge to detect with an electroscope requires hundreds or thousands of volts, so electroscopes are used with high voltage sources such as static electricity and electrostatic machines. An electroscope can only give a rough indication of the quantity of charge; an instrument that measures electric charge quantitatively is called an electrometer. The electroscope was the first electrical measuring instrument. The first electroscope was a pivoted needle (called the ''versorium''), invented by British physician William Gilbert around 1600. a translation by P. Fleury Mottelay of William Gilbert (1600) ''Die Magnete'', London The pith-ball electroscope and the gold-leaf electroscope ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Thomas Edison
Thomas Alva Edison (February 11, 1847October 18, 1931) was an American inventor and businessman. He developed many devices in fields such as electric power generation, mass communication, sound recording, and motion pictures. These inventions, which include the phonograph, the motion picture camera, and early versions of the electric light bulb, have had a widespread impact on the modern industrialized world. He was one of the first inventors to apply the principles of organized science and teamwork to the process of invention, working with many researchers and employees. He established the first industrial research laboratory. Edison was raised in the American Midwest. Early in his career he worked as a telegraph operator, which inspired some of his earliest inventions. In 1876, he established his first laboratory facility in Menlo Park, New Jersey, where many of his early inventions were developed. He later established a botanical laboratory in Fort Myers, Florida, in co ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Carlson2003
Carlson may refer to: * Carlson (name), people with the given name or surname * Carlson Companies, American conglomerate ** CWT, subsidiary ** Radisson Hotel Group, former subsidiary formerly known as Carlson Rezidor * Carlson Inlet, Antarctica * Carlson Library, University of Rochester, New York, USA * Carlson Park, Culver City, California, USA * Carlson's patrol, USMC operation during Guadalcanal campaign * Carlson Stadium, Decorah, Iowa, USA * Carlson's theorem, uniqueness theorem about a summable expansion of an analytic function * Chester County G. O. Carlson Airport Chester County G. O. Carlson Airport is a public airport two miles (3 km) west of Coatesville, in Chester County, Pennsylvania. It is owned by the Chester County Area Airport Authority. Chester County's airport identifier was 40N but it h ..., Coatesville, Pennsylvania, USA * Stromberg-Carlson, American telecommunications equipment manufacturing company See also * Carleson, a surname * Carlsen ( ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Induction Coil
An induction coil or "spark coil" (archaically known as an inductorium or Ruhmkorff coil after Heinrich Rühmkorff) is a type of electrical transformer used to produce high-voltage pulses from a low-voltage direct current (DC) supply. p.98 To create the flux changes necessary to induce voltage in the secondary coil, the direct current in the primary coil is repeatedly interrupted by a vibrating mechanical contact called an interrupter. Invented in 1836 by Nicholas Callan, with additional research by Charles Grafton Page and others, the induction coil was the first type of transformer. It was widely used in x-ray machines, spark-gap radio transmitters, arc lighting and quack medical electrotherapy devices from the 1880s to the 1920s. Today its only common use is as the ignition coils in internal combustion engines and in physics education to demonstrate induction. Construction and function An induction coil consists of two coils of insulated wire wound around a common i ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Edwin Houston
Edwin James Houston (July 9, 1847 – March 1, 1914) was an American electrical engineer, academic, businessman, inventor and writer. Biography Houston was born July 9, 1847, to John Mason and Mary (Lamour) Houston in Alexandria, Virginia. He graduated from Central High School of Philadelphia (a degree-granting institution rather than an ordinary high school) in 1864. He received both his Bachelor of Arts and master's degree from the same Central High School, where he then became professor of civil engineering for a short period before holding its chair of Natural Philosophy and Physical Geography. Princeton University awarded him an honorary doctoral degree. He also served as emeritus professor of physics at the Franklin Institute and professor of physics at the Medico-Chirurgical College. While teaching physics at Central High School in Philadelphia, he helped design an arc light generator with his former student colleague Elihu Thomson. Together, they created the Thomson-H ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Samuel Alfred Varley
Samuel Alfred Varley (1832–1921) was an English electrical engineer. He was one of ten children born to Cornelius Varley and Elizabeth Livermore Straker. Career In 1852, Samuel started work for the Electric Telegraph Company in Manchester. His brother, C. F. Varley, had been employed by the same company since 1849. During the 1850s, Samuel was involved in supervising field telegraphs in the Crimean War. He also published papers on cable signalling. In 1861, Samuel took over the running of a telegraph factory in London, owned by his father. Inventions In 1866, he was among the first to make a self-excited dynamo. Other contenders were Charles Wheatstone and Werner von Siemens Ernst Werner Siemens (von Siemens from 1888; ; ; 13 December 1816 – 6 December 1892) was a German electrical engineer, inventor and industrialist. Siemens's name has been adopted as the SI unit of electrical conductance, the siemens. He foun .... He also invented compound winding for dynamos. ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Leyden Jar
A Leyden jar (or Leiden jar, or archaically, sometimes Kleistian jar) is an electrical component that stores a high-voltage electric charge (from an external source) between electrical conductors on the inside and outside of a glass jar. It typically consists of a glass jar with metal foil cemented to the inside and the outside surfaces, and a metal terminal projecting vertically through the jar lid to make contact with the inner foil. It was the original form of capacitor (also called a ''condenser''). Its invention was a discovery made independently by German cleric Ewald Georg von Kleist on 11 October 1745 and by Dutch scientist Pieter van Musschenbroek of Leiden (Leyden), Netherlands in 1745–1746. The Leyden jar was used to conduct many early experiments in electricity, and its discovery was of fundamental importance in the study of electrostatics. It was the first means of accumulating and preserving electric charge in large quantities that could be discharged at the exp ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Joseph Henry
Joseph Henry (December 17, 1797– May 13, 1878) was an American scientist who served as the first Secretary of the Smithsonian Institution. He was the secretary for the National Institute for the Promotion of Science, a precursor of the Smithsonian Institution. He was highly regarded during his lifetime. While building electromagnets, Henry discovered the electromagnetic phenomenon of self-inductance. He also discovered mutual inductance independently of Michael Faraday, though Faraday was the first to make the discovery and publish his results. Henry developed the electromagnet into a practical device. He invented a precursor to the electric doorbell (specifically a bell that could be rung at a distance via an electric wire, 1831) and electric relay (1835). His work on the electromagnetic relay was the basis of the practical electrical telegraph, invented by Samuel F. B. Morse and Sir Charles Wheatstone, separately. In his honor the SI unit of inductance is named the henry (p ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
