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The SI unit of electrical charge is the coulomb, which has the abbreviation "C". The symbol Q is used in equations to represent the quantity of electric charge. For example, "Q = 0.5 C" means "the quantity of electric charge is 0.5 coulomb".

1 History

According to Thales of Miletus, writing circa 600 BC, electricity was known to the Ancient Greeks, who found that rubbing fur on various substances, such as amberThis is about the material called amber. For other things called amber, see Amber (disambiguation). Amber is a fossil resin much used for the manufacture of ornamental objects. Although not mineralized it is sometimes considered and used as a gemstone., would cause a particular attractionIn general, Attraction is a force, that moves one object to another. Science See gravity''. Attraction in Humans Interpersonal attraction is what leads two people to form friendships and romantic relationships. Grammar Attraction is the process by which a between the two. The Greeks noted that the amber buttons could attract light objects such as hairHair is also a musical: see Hair (musical) and Hair (movie Hair is the filamentous outgrowth of the epidermis found in mammals. Hair is a characteristic of all mammals, though in some species hair is absent at certain stages of life. Hairs" are also found, and that if they rubbed the amber for long enough, they could even get a sparkA spark can trigger a fire. A spark may be a small airborne ember from a fire. Spark98 is a name for a specific software distribution. by David O'Hallaron A spark gap can create an electric spark or electric voltaic arc Spark is a small Trotskyist group i to jump.

An object found in Iraq in 1938Events January -June January 3 The March of Dimes is established by Franklin Delano Roosevelt. January 11 Frances Moulton is the first woman to become president of a US national bank. January 20 Wedding of king Farouk I of Egypt and Farida Zulficar in Cai, dated to about 250 BCCenturies: 4th century BC 3rd century BC 2nd century BC Decades: 300s BC 290s BC 280s BC 270s BC 260s BC 250s BC 240s BC 230s BC 220s BC 210s BC 200s BC Years: 255 BC 254 BC 253 BC 252 BC 251 BC 250 BC 249 BC 248 BC 247 BC 246 BC 245 BC Events Bactria gai and called the Baghdad BatteryThe Baghdad Battery is the common name for a number of artifacts apparently discovered in the village of Khuyut Rabbou'a (near Baghdad, Iraq) in 1936. These artifacts came to wider attention in 1938, when Wilhelm Konig, the German director of the National, 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 anachronisticAn anachronism (from Greek ana back, and chronos time) is an artifact that belongs to another time, a person who seems to be displaced in time (i. who belongs to another age) or something located at a time when it could not have existed or occurred. One o descriptions of electrical devices on Egyptian walls and in ancient writings.

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 invented an early electrostatic generator. Other European pioneers were Robert Boyle, who stated in 1675 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 electric charge that would later be called positive and negative. The Leyden jar, a type of capacitor for storing electric charge 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 charge. 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 Samuel Morse, inventor of the telegraph; Alexander Graham Bell, 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, inventor of alternating current.

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 transmission was eventually adopted as the standard.