History of Electricity
According to Thales of Miletus, writing circa 600 BCE, a form of electricity was known to the Ancient Greeks, who found that rubbing fur on various substances, such as amber, would cause a particular attraction between the two. The Greeks noted that the amber buttons could attract light objects such as hair, and that if they rubbed the amber for long enough, they could even get a spark to jump. This is the origin of the word "electricity", from the Greek ēlektron = "amber", which came from an old root ēlek- = "shine".
An object found in Iraq in 1938, dated to about 250 BCE and called the Baghdad Battery, resembles an electrochemical cell and is believed by some to have been used for electroplating. There is no firm documentary evidence to indicate what the object was used for, though. There are other descriptions of supposedly electrical devices on Egyptian walls, such as the Dendera light. Other devices discovered in Egyptian and other archaeological digs have been alleged to be electrical batteries.
In 1600 the English scientist William Gilbert returned to the subject in De Magnete, and coined the modern Latin word electricus from ηλεκτρον (elektron), the Greek word for "amber", which soon gave rise to the English words electric and electricity. He was followed in 1660 by Otto von Guericke, who is regarded as having invented an early electrostatic generator. Other European pioneers were Robert Boyle, who in 1675 stated that electric attraction and repulsion can act across a vacuum; Stephen Gray, who in 1729 classified materials as conductors and insulators; and C. F. Du Fay, who first identified the two types of electricity that would later be called positive and negative. The Leyden jar, a type of capacitor for electrical energy in large quantities, was invented at Leiden University by Pieter van Musschenbroek in 1745. William Watson, experimenting with the Leyden jar, discovered in 1747 that a discharge of static electricity was equivalent to an electric current.
In June, 1752, Benjamin Franklin promoted his investigations of electricity and theories through the famous, though extremely dangerous, experiment of flying a kite during a thunderstorm. Following these experiments he invented a lightning rod and established the link between lightning and electricity. If Franklin did fly a kite in a storm, he did not do it the way it is often described (as it would have been dramatic but fatal). It was either Franklin (more frequently) or Ebenezer Kinnersley of Philadelphia (less frequently) who created the convention of positive and negative electricity.
As a result of this discovery, the Chinese word for "lightning" is now also used to mean "electricity".
Franklin's observations aided later scientists such as Michael Faraday, Luigi Galvani, Alessandro Volta, André-Marie Ampère, and Georg Simon Ohm whose work provided the basis for modern electrical technology. The work of Faraday, Volta, Ampere, and Ohm is honored by society, in that fundamental units of electrical measurement are named after them.]
Volta worked with chemicals and discovered that chemical reactions could be used to create positively charged anodes and negatively charged cathodes. When a conductor was attached between these, the difference in the electrical potential (also known as voltage) drives a current between them through the conductor. The potential difference between two points is measured in units of volts in recognition of Volta's work.
The late 19th and early 20th century produced such giants of electrical engineering as Nikola Tesla, inventor of the induction motor and the fundamental alternating current transmission system, Samuel Morse, inventor of the telegraph; Antonio Meucci, inventor of the telephone; Thomas Edison (inventor of the phonograph and a practical incandescent light bulb); George Westinghouse, inventor of the electric locomotive; Charles Steinmetz, theoretician of alternating current.
Nikola Tesla performed experiments with very high voltages that are the stuff of legend, involving ball lightning and other effects (some have been duplicated or explained; and others which have not). Nikola Tesla, inventor of the induction motor and deveIn May 1885, Westinghouse, then president of the Westinghouse Electric Company in Pittsburgh, Pennsylvania, bought the rights to Tesla's patents for polyphase alternating-current dynamos. This led to a contest in the so-called court of public opinion as to which system would be adopted as the standard for power transmission (known Edison's direct-current system or Westinghouse's alternating-current method.
Edison conducted a spirited public relations campaign which included his promotion of the electric chair as a method of execution. The electric chair ran on Westinghouse's AC; Edison wanted to prove that AC power was capable of killing, and should therefore be viewed by the public as inherently dangerous. This fear, uncertainty and doubt campaign included the electrocution of Topsy the Elephant. AC power was eventually adopted as the standard.
