History of electricity
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History of electricity

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History of electricity History of electricity Presentation Transcript

  •  Ancient Egyptians were aware of shocks when interacting with electric fish such as the electric catfish or other animals such as electric eels. The shocks from animals were apparent to observers since pre-history by a variety of peoples that came into contact with them. Texts from 2750 BC by the ancient Egyptians referred to these fish as "thunderer of the Nile" and saw them as the "protectors" of all the other fish.
  •  Thales of Miletus, writing at around 600 BC, noted that rubbing fur on various substances, such as amber would cause them to attract specks of dust and other light objects. Thales wrote on the effect now known as static electricity. The Greeks noted that if they rubbed the amber for long enough they could even get an electric spark to jump.
  •  Archbishop Eustathius of Thessalonica, Greek scholar and writer of the 12th century, records that Woliver, king of the Goths, was able to draw sparks from his body. The same writer states that a certain philosopher was able while dressing to draw sparks from his clothes, a result seemingly akin to that obtained by Robert Symmer in his silk stocking experiments, a careful account of which may be found in the Philosophical Transactions, 1759.
  •  Toward the late 16th century, a physician of Queen Elizabeths time, Dr. William Gilbert, in De Magnete, expanded on Cardanos work and invented the New Latin word electricusfrom ἤλεκτρον (elektron), the Greek word for "amber"Gilbert undertook a number of careful electrical experiments, in the course of which he discovered that many substances other than amber, such as sulphur, wax, glass, etc.,were capable of manifesting electrical properties. Gilbert also discovered that a heated body lost its electricity and that moisture prevented the electrification of all bodies, due to the now well-known fact that moisture impaired the insulation of such bodies. He also noticed that electrified substances attracted all other substances indiscriminately, whereas a magnet only attracted iron.
  • Robert Boyle (1627—1691), in 1675, stated that electric attraction and repulsion can act across a vacuum. One of his important discoveries was that electrified bodies in a vacuum would attract light substances, this indicating that the electrical effect did not depend upon the air as a medium. He also added resin to the then known list of electrics.[
  •  This was followed in 1660 by Otto von Guericke, who invented an early electrostatic generator. By the end of the 17th Century, researchers had developed practical means of generating electricity by friction with an electrostatic generator, but the development of electrostatic machines did not begin in earnest until the 18th century, when they became fundamental instruments in the studies about the new science of electricity.
  •  The electric machine was subsequently improved by Francis Hauksbee, Litzendorf, and by Prof. Georg Matthias Bose, about 1750. Litzendorf substituted a glass ball for the sulphur ball of Guericke. Boze was the first to employ the "prime conductor" in such machines, this consisting of an iron rod held in the hand of a person whose body was insulated by standing on a block of resin. Ingenhousz, during 1746, invented electric machines made of plate glass. Experiments with the electric machine were largely aided by the discovery of the property of a glass plate, when coated on both sides with tinfoil, of accumulating a charge of electricity when connected with a source of electromotive force. The electric machine was soon further improved by Andrew Gordon, a Scotsman, Professor at Erfurt, who substituted a glass cylinder in place of a glass globe; and by Giessing of Leipzig who added a "rubber" consisting of a cushion of woollen material. The collector, consisting of a series of metal points, was added to the machine by Benjamin Wilson about 1746, and in 1762, John Canton of England (also the inventor of the first pith-ball electroscope) improved the efficiency of electric machines by sprinkling an amalgam of tin over the surface of the rubber.
  •  Generator built by Francis Hauksbee.
  •  n 1729, Stephen Gray conducted a series of experiments that demonstrated the difference between conductors and non- conductors (insulators), showing amongst other things that a metal wire and even pack thread conducted electricity, whereas silk did not. In one of his experiments he sent an electric current through 800 feet of hempen thread which was suspended at intervals by loops of silk thread. When he tried to conduct the same experiment substituting the silk for finely spun brass wire, he found that the electric current was no longer carried throughout the hemp cord, but instead seemed to vanish into the brass wire. From this experiment he classified substances into two categories: "electrics" like glass, resin and silk and "non-electrics" like metal and water. "Electrics" conducted charges while "non- electrics" held the charge.
  •  In 1732, C. F. du Fay began to conduct several experiments. In his first experiment, Du Fay concluded that all objects except metals, animals, and liquids could be electrified by rubbing and that metals, animals and liquids could be electrified by means of an electric machine, thus discrediting Grays "electrics" and "non-electrics" classification of substances.
  •  The Leyden jar, a type of capacitor for electrical energy in large quantities, was invented independently by Ewald Georg von Kleist on 11 October 1744 and by Pieter van Musschenbroek in 1745—1746 at Leiden University (the latter location giving the device its name).[35] William Watson, when experimenting with the Leyden jar, discovered in 1747 that a discharge of static electricity was equivalent to an electric current. Capacitance was first observed by Von Kleist of Leyden in 1754. Von Kleist happened to hold, near his electric machine, a small bottle, in the neck of which there was an iron nail. Touching the iron nail accidentally with his other hand he received a severe electric shock. In much the same way Musschenbroeck assisted by Cunaens received a more severe shock from a somewhat similar glass bottle. Sir William Watson of England greatly improved this device, by covering the bottle, or jar, outside and in with tinfoil. This piece of electrical apparatus will be easily recognized as the well-known Leyden jar, so called by the Abbot Nollet of Paris, after the place of its discovery.
  • Benjamin Franklin (1706- 1790)His kite experiment demonstrated that lightning is electricity. He was the first to use the terms positive and negative charge.Franklin was one of seventeen children. He quit school at age ten to become a printer. His life is the classic story of a self-made man achieving wealth and fame through determination and intelligence.
  •  About 1784 C. A. Coulomb, after whom is named the electrical unit of quantity, devised the torsion balance, by means of which he discovered what is known as Coulombs law; — The force exerted between two small electrified bodies varies inversely as the square of the distance; not as Aepinus in his theory of electricity had assumed, merely inversely as the distance. According to the theory advanced by Cavendish "the particles attract and are attracted inversely as some less power of the distance than the cube." A large part of the domain of electricity became virtually annexed by Coulombs discovery of the law of inverse squares.
  •  In 1800 Alessandro Volta constructed the first device to produce a large electric current, later known as the electric battery. Napoleon, inform ed of his works, summoned him in 1801 for a command performance of his experiments. He received many medals and decorations, including the Légion dhonneur.
  •  Andre Marie Ampère who shortly thereafter (1821) announced his celebrated theory of electrodynamics, relating to the force that one current exerts upon another, by its electro-magnetic effects, namely Two parallel portions of a circuit attract one another if the currents in them are flowing in the same direction, and repel one another if the currents flow in the opposite direction. Two portions of circuits crossing one another obliquely attract one another if both the currents flow either towards or from the point of crossing, and repel one another if one flows to and the other from that point. When an element of a circuit exerts a force on another element of a circuit, that force always tends to urge the second one in a direction at right angles to its own direction.
  •  Georg Simon Ohm did his work on resistance in the years 1825 and 1826, and published his results in 1827 as the book Die galvanische Kette, mathematisch bearbeitet. He drew considerable inspiration from Fouriers work on heat conduction in the theoretical explanation of his work. For experiments, he initially used voltaic piles, but later used a thermocouple as this provided a more stable voltage source in terms of internal resistance and constant potential difference.
  •  Michael Faraday (1791-1867) an Englishman, made one of the most significant discoveries in the history of electricity: Electromagnetic induction. His pioneering work dealt with how electric currents work. Many inventions would come from his experiments, but they would come fifty to one hundred years later. Failures never discouraged Faraday. He would say; "the failures are just as important as the successes." He felt failures also teach. The farad, the unit of capacitance is named in the honor of Michael Faraday.
  •  In 1853 Sir William Thomson (later Lord Kelvin) predicted as a result of mathematical calculations the oscillatory nature of the electric discharge of a condenser circuit. To Henry, however, belongs the credit of discerning as a result of his experiments in 1842 the oscillatory nature of the Leyden jar discharge. He wrote:[93] The phenomena require us to admit the existence of a principal discharge in one direction, and then several reflex actions backward and forward, each more feeble than the preceding, until the equilibrium is obtained.
  •  James Maxwell (1831- 1879) a Scottish mathematician translated Faradays theories into mathematical expressions. Maxwell was one of the finest mathematicians in history. A maxwell is the electromagnetic unit of magnetic flux, named in his honor. Today he is widely regarded as secondary only to Isaac Newton and Albert Einstein in the world of science.
  •  Nikola Tesla was born of Serbian parents July 10, 1856 and died a broke and lonely man in New York City January 7, 1943. He envisioned a world without poles and power lines. Referred to as the greatest inventive genius of all time. Teslas system triumphed to make possible the first large- scale harnessing of Niagara Falls with the first hydroelectric plant in the United States in 1886.
  •  Heinrich Hertz (1857- 1894) a German physicist, laid the ground work for the vacuum tube. He laid the foundation for the future development of radio, telephone, telegrap h, and even television. He was one of the first people to demonstrate the existence of electric waves. Hertz was convinced that there were electromagnetic waves in space.
  •  Hendrik Lorentz introduced a strict separation between matter (electrons) and ether, whereby in his model the ether is completely motionless, and it wont be set in motion in the neighborhood of ponderable matter. Contrary to other electron models before, the electromagnetic field of the ether appears as a mediator between the electrons, and changes in this field can propagate not faster than the speed of light.
  •  Henri Poincaré between 1895 and 1905 formulated on many occasions the Principle of Relativity and tried to harmonize it with electrodynamics. He declared simultaneity only a convenient convention which depends on the speed of light, whereby the constancy of the speed of light would be a useful postulate for making the laws of nature as simple as possible.
  •  The first formulation of a quantum theory describing radiation and matter interaction is due to Paul Adrien Maurice Dirac, who, during 1920, was first able to compute the coefficient of spontaneous emission of an atom. Paul Dirac described the quantization of the electromagnetic field as an ensemble of harmonic oscillators with the introduction of the concept of creation and annihilation operators of particles