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2009-06-20 02:14:46 UTC
Grazie in anticipo a tutti ^^
Thomas Alva Edison was born in Milan on the February 11, 1847. He was an American inventor who developed many devices that greatly influenced the life around the world, including the phonograph and the electric chair. Most people think he invented the electric light bulb, but he really only improved it, to make it last long enough to help people see in the dark. He was one of the first inventors to apply the principles of mass production and large teamwork to the process of invention, and therefore is often credited with the creation of the first industrial research laboratory.
Edison is considered one of the most prolific inventors in history, holding 1.093 patents in his name, as well as many patent in United Kingdom, France and Germany. He is credited with numerous invention that contributed to mass communication and, in particular, telecommunication. His advanced work in these fields was an outgrowth of his early career as a telegrapher operator. Edison originated the concept and implementation of electric-power generation and distribution to homes, business, and factories - a crucial development in the modern industrialized world. His first power plant was on Manhattan Island, New York.
Edison patented an electric distribution system in 1880, which was essential to capitalize on the invention of the electric lamp. On December 17, 1880, Edison founded the Edison Electric Illuminating Company. The company established the first investor-owned electric utility in 1882 on Pearl Street Station, New York City. It was on September 4, 1882, that Edison switched on his Pearl Street generating station's electrical power distribution system, which provided 110 volts direct current (DC) to 59 customers in lower Manhattan.
Earlier in the year, in January 1882 he had switched on the first steam generating power station at Holborn Viaduct in London. The DC supply system provided electricity supplies to street lamps and several private dwellings within a short distance of the station. On January 19, 1883, the first standardized incandescent electric lighting system employing overhead wires began service in Roselle, New Jersey.
War of currents
Extravagant displays of electric lights quickly became a feature of public events, as this picture from the 1897 Tennessee Centennial Exposition shows.
Edison's true success, like that of his friend Henry Ford, was in his ability to maximize profits through establishment of mass-production systems and intellectual property rights. This dampened the success of less profitable work by others who were focused on inventing longer-lasting high-efficiency technology. George Westinghouse and Edison became adversaries because of Edison's promotion of direct current for electric power distribution instead of the more easily transmitted alternating current (AC) system invented by Nikola Tesla and promoted by Westinghouse. Unlike DC, AC could be stepped up to very high voltages with transformers, sent over thinner and cheaper wires, and stepped down again at the destination for distribution to users.
In 1887 there were 121 Edison power stations in the United States delivering DC electricity to customers. When the limitations of Direct Current (DC) were discussed by the public, Edison launched a propaganda campaign to convince people that Alternating Current (AC) was far too dangerous to use. The problem with DC was that the power plants could only economically deliver DC electricity to customers about one and a half miles from the generating station, so it was only suitable for central business districts. When George Westinghouse suggested using high-voltage AC instead, as it could carry electricity hundreds of miles with marginal loss of power, Edison waged a "War of Currents" to prevent AC from being adopted.
Despite Edison's contempt for capital punishment, the war against AC led him to become involved in the development and promotion of the electric chair as a demonstration of AC's greater lethal potential versus the "safer" DC. Edison went on to carry out a brief but intense campaign to ban the use of AC or to limit the allowable voltage for safety purposes. As part of this campaign, Edison's employees publicly electrocuted animals to demonstrate the dangers of AC; AC electric currents, particularly near 60 Hz frequency, have a markedly greater potential for inducing fatal “Cardiac Fibrillation” than do DC currents. On one of the more notable occasions, in 1903, Edison's workers electrocuted Topsy the elephant at Luna Park, near Coney Island, after she had killed several men and her owners wanted her put to death. His company filmed the electrocution.
AC replaced DC in most instances of generation and power d