Dictionary:

electricity

  (ĭ-lĕk-trĭs'ĭ-tē, ē'lĕk-)

1. 1. The physical phenomena arising from the behavior of electrons and protons that is caused by the attraction of particles with opposite charges and the repulsion of particles with the same charge.
   2. The physical science of such phenomena.
2. Electric current used or regarded as a source of power.
3. Intense, contagious emotional excitement.

Physical phenomena involving electric charges, their motions, and their effects. The motion of a charge is affected by its interaction with the electric field and, for a moving charge, the magnetic field. The electric field acting on a charge arises from the presence of other charges and from a time-varying magnetic field. The magnetic field acting on a moving charge arises from the motion of other charges and from a time-varying electric field. Thus electricity and magnetism are ultimately inextricably linked. In many cases, however, one aspect may dominate, and the separation is meaningful. See also Electric charge; Electric field; Magnetism.

The quantitative development of electricity began late in the eighteenth century. J. B. Priestley in 1767 and C. A. Coulomb in 1785 discovered independently the inverse-square law for stationary charges. This law serves as a foundation for electrostatics. See also Coulomb's law; Electrostatics.

In 1800 A. Volta constructed and experimented with the voltaic pile, the predecessor of modern batteries. It provided the first continuous source of electricity. In 1820 H. C. Oersted demonstrated magnetic effects arising from electric currents. The production of induced electric currents by changing magnetic fields was demonstrated by M. Faraday in 1831. In 1851 he also proposed giving physical reality to the concept of lines of force. This was the first step in the direction of shifting the emphasis away from the charges and onto the associated fields. See also Electromagnetic induction; Electromagnetism; Lines of force.

In 1865 J. C. Maxwell presented his mathematical theory of the electromagnetic field. This theory, which proposed a continuous electric fluid, not only synthesized a unified theory of electricity and magnetism, but also showed optics to be a branch of electromagnetism. See also Electromagnetic radiation; Maxwell's equations.

The developments of theories about electricity subsequent to Maxwell have all been concerned with the microscopic realm. Faraday's experiments on electrolysis in 1833 had indicated a natural unit of electric charge, thus pointing toward a discrete rather than continuous charge. The existence of electrons, negatively charged particles, was postulated by A. Lorenz in 1895 and demonstrated by J. J. Thomson in 1897. The existence of positively charged particles (protons) was shown shortly afterward (1898) by W. Wien. Since that time, many particles have been found having charges numerically equal to that of the electron. The question of the fundamental nature of these particles remains unsolved, but the concept of a single elementary charge unit is apparently still valid. See also Baryon; Electrolysis; Electron; Elementary particle; Hyperon; Meson; Proton; Quarks.

The sources of electricity in modern technology depend strongly on the application for which they are intended.

The principal use of static electricity today is in the production of high electric fields. Such fields are used in industry for testing the ability of components such as insulators and condensers to withstand high voltages, and as accelerating fields for charged-particle accelerators. The principal source of such fields today is the Van de Graaff generator. See also Particle accelerator.

The major use of electricity arises in devices using direct current and low-frequency alternating current. The use of alternating current, introduced by S. Z. de Ferranti in 1885–1890, allows power transmission over long distances at very high voltages with a resulting low-percentage power loss followed by highly efficient conversion to lower voltages for the consumer through the use of transformers. See also Alternating current; Electric current.

Large amounts of direct current are used in the electrodeposition of metals, both in plating and in metal production, for example, in the reduction of aluminum ore. See also Direct current; Electrochemistry; Electrometallurgy; Electroplating of metals.

The principal sources of low-frequency electricity are generators based on the motion of a conducting medium through a magnetic field. The moving charges interact with the magnetic field to give a charge motion that is normal to both the direction of motion and the magnetic field. In the most common form, conducting wire coils rotate in an applied magnetic field. The rotational power is derived from a water-driven turbine in the case of hydroelectric generation, or from a gas-driven turbine or reciprocating engine in other cases. See also Alternating-current generator; Direct-current generator; Electric power generation; Generator.

Many high-frequency devices, such as communications equipment, television, and radar, involve the consumption of only moderate amounts of power, generally derived from low-frequency sources. If the power requirements are moderate and portability is needed, the use of ordinary chemical batteries is possible. Ion-permeable membrane batteries are a later development in this line. Fuel cells, particularly hydrogen-oxygen systems, are being developed. They have already found extensive application in earth satellite and other space systems. The successful use of thermoelectric generators based on the Seebeck effect in semiconductors has been reported. See also Battery; Fuel cell; Ion-selective membranes and electrodes.

The solar battery, also a semiconductor device, has been used to provide charging current for storage batteries in telephone service and in communications equipment in artificial satellites. See also Solar cell.

Direct conversion of mechanical energy into electrical energy is possible by utilizing the phenomena of piezoelectricity and magnetostriction. These have some application in acoustics and stress measurements. Pyroelectricity is a thermodynamic corollary of piezoelectricity. See also Magnetostriction; Piezoelectricity; Pyroelectricity.

The flow of electrons in a circuit. The speed of electricity is the speed of light (approximately 186,000 miles per second or 300,000,000 meters per second). In a wire, it is slowed due to the resistance in the material.

Its pressure, or force, is measured in "volts," and its flow, or current, is measured in "amperes" or simply "amps." The amount of work it produces is measured in "watts" (amps X volts).

For more information on electricity, visit Britannica.com.

Electricity was discovered by Benjamin Franklin in 1752. The electric generator was invented by Michael Faraday in 1831. Thomas Edison's invention of the electric lightbulb in 1879 sparked the demand for electric power that continues to this day, and initiated the need for legislative and regulatory controls on the electric-power-generating industry.

History

By the end of the nineteenth century, the United States had completed its transition from using wood as a major energy source to using coal, and the next transition from coal to oil and natural gas was just beginning. By the early twentieth century, both homes and businesses increased their demand for electric power, and electric utilities obtained long-term franchises from municipalities.

In 1920, the Federal Power Act (16 U.S.C.A. §§ 791a-828c) was passed in response to increased competition between electric utilities and to a lack of consistent service to rural areas. The Federal Power Act gave the Federal Power Commission the authority to license hydroelectric plants. Later, President Franklin D. Roosevelt encouraged Congress to create part II of the act, which gave the Federal Power Commission the power to regulate the transmission of electric energy (16 U.S.C.A. §§ 824-824m). This legislation was necessary to guard against potential abuses of the utility companies' monopolistic structure and to ensure adequate and consistent service nationwide.

As more and larger electric generating plants were constructed and as more electric power lines were strung, legislators believed that through economies of scale, electric utility monopolies could actually offer lower costs to consumers than could competition between smaller utilities. Because of the capital-intensive nature of providing electric power, and the sunken costs of building plants and stringing lines, it is more cost-effective to spread these costs over the large and consistent customer base provided by a monopoly.

Structure of the Industry

Modern electric utilities have three major organizational components: generation (power plants), transmission (high-voltage bulk power between utilities), and distribution (low-voltage power to ultimate consumers). Modern electric utilities not only produce the power they need for their consumers but also pool and coordinate excess electricity with other utilities.

In 1995, a total of thirty-five hundred electric utilities around the United States had the ability to produce over 640 million megawatts of electrical energy. Pooling and coordination of electrical energy take place through high-voltage wires that are maintained and referred to as the national grid; high-voltage wires are used because they allow transmission at a lower current, which generates less heat and results in less energy loss. At regional distribution centers closer to the ultimate consumers, the electrical energy is transformed into the low-voltage, higher-current electricity delivered to homes and businesses.

Major electric utilities produce electric power by burning coal, harnessing the hydroelectric energy produced by dams, and initiating and maintaining nuclear fission. Smaller, independent power producers use hydroelectric energy in addition to wood energy, geothermal energy, and biomass, which are all forms of renewable energy. Nuclear electric generating plants were constructed after the passage of the Atomic Energy Act (42 U.S.C.A. § 2011), which removed the government's monopoly over nuclear power, in 1946, and the Price-Anderson Act (42 U.S.C.A. § 2210), which allowed for private ownership of uranium, in 1957. Commercial nuclear energy expanded in the 1960s and the early 1970s, and most consumers welcomed what was thought to be a safe and inexpensive source of energy. From the late 1970s to the 1990s, the dangers of nuclear energy and the expense of environmental contamination and lack of safe waste storage contributed to the end of nuclear power plant construction. No U.S. nuclear power plants have been ordered since 1978. Coal and hydroelectric energy continue to be the principal sources of commercial electric power.

Modern Legislation and Regulation of the Industry

The generation, transmission, and distribution of electric power are heavily regulated. At the federal level, the transmission of electric power between utilities is governed by the Public Utilities Regulatory Policies Act (PURPA) (Pub. L. No. 95-617 [codified in various sections of U.S.C.A. tits. 15, 16]). In PURPA, Congress gave the Federal Energy Regulatory Commission jurisdiction over energy transmission. PURPA requires that independent power producers (IPPs) be allowed to interconnect with the distribution and transmission grids of major electric utilities. In addition, PURPA protects these IPPs from paying burdensome rates for purchasing backup power from these utilities, and sets the rate at which the utilities can purchase power from these IPPs at the major utilities' "avoided cost" (market cost minus the production costs "avoided" by purchasing from another utility) of producing the power.

The primary regulation of the generation, distribution, and transmission of electric power occurs at the state level through various state public utility commissions. Because the production of electric energy is connected with a public interest, states have a vested interest in overseeing it and working to guarantee that electricity will be produced in a safe, efficient, and expedient manner. In exchange for a monopoly in a particular geographic region, an electric utility must agree to supply electricity continuously and has a duty to avert unreasonable risks to its consumers. Electric utility companies must provide electricity at applicable lawful rates, and must file rate schedules with the public service commissions. Sometimes these rates are challenged, and administrative hearings are held to allow the utilities to petition for rate increases. Electricity rates must be high enough to cover the cost of production and must allow a fair return on the current value of capital investment. Rates that would allow significantly more than a fair return may be struck down as unreasonably high.

Dangers and Liabilities

Electricity, especially at high voltages or high currents, is a dangerous commodity. Faulty wiring, power lines that are close to trees and buildings, and inadequate warning signs and fences around transformer stations and over buried electrical cables can subject an individual to electric shock or even electrocution. Because of the ultrahazardous nature of providing electric power, states have many statutes and regulations in place to protect the public from electric shock.

Other dangers from electricity include stray voltage and electromagnetic field radiation. Stray voltage affects farm animals, especially dairy cattle. On dairy farms, it occurs when cattle drink from electric feeding troughs or are attached to electric milking machines, and small electric shocks pass through the cattle, through their hooves, and into the ground. Repeated shocks can inhibit or destroy the milk-producing capability of dairy cattle. Liability for stray voltage on farms can be attributed to public utilities when wiring is faulty or negligently connected to a farmer's equipment. Some juries have awarded thousands of dollars to farmers whose cattle have been damaged by this phenomenon.

Electromagnetic fields are created whenever current moves through power lines. The strength of these fields drops off exponentially as the distance from the power lines increases. Individuals whose homes or businesses are close to power wires must live and work in these fields. Some individuals who live or work near high-voltage power lines have developed brain cancer and leukemia, and blame their condition on the constant exposure to electromagnetic field radiation. Studies have shown a correlation between electromagnetic fields and cancer, but many of the studies have been challenged as methodologically flawed. By the mid-1990s, no conclusive scientific evidence proved an epidemiological relationship between cancer and the electromagnetic fields produced by high-voltage power lines.

A flow of electrical charges, such as electrons, through a conductor.

Science states that certain particles possess a force field or charge. The charge possessed by an electron is negative while the charge possessed by a proton is positive. Electricity can be divided into two groups, static and dynamic. Static electricty deals with charges at rest and dynamic electricity deals with charges in motion.

The Greeks and other ancient peoples knew that some substances attract others when one of them has been rubbed. Similarly, they must have encountered mild shocks. People still notice both today, as when clothing picks up lint without touching it or when a doorknob gives a slight shock on a dry winter's day. Thales, often counted as the first scientist, investigated the attractive properties of rubbed amber in Ionia around 600 bce. He compared it to magnetism and noted that it was similar, but different. More than 2000 years later, around 1570, the English scientist William Gilbert also studied magnetism and the corresponding attraction of rubbed amber and various rubbed jewels. He modified the Greek and Latin terms for amber to produce the English word electric as a noun describing a material that behaved like amber. Nearly a hundred years later, in 1650, the term electricity was coined to refer to the force itself.

In the same year that electricity entered English, a German scientist, Otto von Guericke, was working with a method he had developed for making more electricity than could be made by rubbing a small piece of amber. He worked with a different electric, sulfur. He formed this electric into a ball, so it could be rubbed continuously by rotating it. Von Guericke was the first to observe light produced by electricity. Similar experiments produced light from electricity in England.

The electricity produced by von Guericke faded away soon after the ball stopped rotating. Shocks and lights were evanescent experiences. About a hundred years after the use of rotating balls, however, scientists in Leyden (Leiden, the Netherlands) learned that electricity could be stored in water in glass jars and conducted in and out with metal wires or nails. Modern versions are somewhat different in construction, but the main impact of the Leiden jar was the same. A large charge could be stored up over time and then released by touching the conductor. Some terrific shocks resulted, and the jars became popular in parlors as well as with scientists.

Still, no one knew what electricity was. It was not even clear whether there was one type or two (different electrics attracted or repelled different light substances, although the shocks seemed to be the same). Accidentally, a scientist in Italy, Luigi Galvani, found that severed frogs' legs twitched in response to electricity and that they also responded the same way when touching metal that was not charged. Another Italian, Alessandro Volta, who had been experimenting with electricity, found that the reaction was chemical. He built an apparatus, which came to be known as the voltaic pile, that offered the first method of producing electricity in any quantity without rubbing. Improvements on the voltaic pile are the familiar batteries of today.

The main difference between electricity stored in a Leiden jar and that released by a battery is that chemically produced electricity does not all rush out at once. Instead, a steady flow like the current of a river appears. For the first time, electricity became available for periods of time, instead of instants.

Within 20 years, the next key event occurred, also by accident. Hans Christian Oersted discovered that the connection between electricity and magnetism, suspected since at least the time of Thales, was real. An electric current could produce magnetic effects. In another ten years the converse was shown, and magnets were being used to generate electric currents. With the development of powerful currents produced by magnetic generators, the stage was set for the use of electric power for light, for communication, and for production of motion.

n.

The power that causes all natural phenomena not known to be caused by something else. It is the same thing as lightning, and its famous attempt to strike Dr. Franklin is one of the most picturesque incidents in that great and good man's career. The memory of Dr. Franklin is justly held in great reverence, particularly in France, where a waxen effigy of him was recently on exhibition, bearing the following touching account of his life and services to science:

        "Monsieur Franqulin, inventor of electricity.  This 
    illustrious savant, after having made several voyages around the 
    world, died on the Sandwich Islands and was devoured by savages, 
    of whom not a single fragment was ever recovered."

Electricity (from New Latin ēlectricus, "amberlike") is a general term for a variety of phenomena resulting from the presence and flow of electric charge. This includes many well-known physical phenomena such as lightning, electromagnetic fields and electric currents, and is put to use in industrial applications such as electronics and electric power. These related, but distinct, concepts are better identified by more precise terms:

• Electric field — an effect produced by an electrically charged object that exerts a force on other charged objects in its vicinity.
• Electric potential — the capacity of an electric field to do work, typically measured in volts (V).
• Electric current — a movement or flow of electrically charged particles, typically measured in amperes (A).
• Electrical energy — the energy made available by the flow of electric charge through an electrical conductor.
• Electric power — the rate at which electric energy is converted to or from another energy form, such as light, heat, or mechanical energy.
• Electric charge — a connection conserved property of some subatomic particles, which determines their electromagnetic interactions. Electrically charged matter is influenced by, and produces, electromagnetic fields.
• Electromagnetism — a fundamental interaction

History of electricity

Main articles: History of electricity and Etymology of electricity

Static electricity produced by rubbing objects against fur was known to the ancient Greeks, Phoenicians, Parthians and Mesopotamians. Some propose that the Parthians and Mesopotamians may have had some knowledge of electroplating, based on the discovery of the Baghdad Battery, which resembles a galvanic cell, although this is disputed by many scholars.

In 1600 the English scientist William Gilbert first used the New Latin word electricus ("of amber" or "like amber", from ηλεκτρον [elektron], the Greek word for "amber") to refer to the property of attracting small objects after being rubbed. This soon gave rise to the English words "electric" and "electricity", in Sir Thomas Browne's Pseudodoxia Epidemica of 1646.

Further work was conducted by Otto von Guericke, Robert Boyle, Stephen Gray and C. F. du Fay. In the 18th century, Benjamin Franklin conducted extensive research in electricity. He had theories on the relationship between lightning and static electricity, including his famous kite-flying experiment,which was a key attached to a wet string and kite. During a lightning storm a small spark struck his finger showing that lightning is electricity. This experiment was proved false on an episode of mythbusters on the episode entitled "Franklin's Kite" where it was shown that the electricity carried down the string would have been enough to kill him. It sparked the interest of later scientists whose work provided the basis for modern electrical technology. Most notably these include Luigi Galvani (1737–1798), Alessandro Volta (1745-1827), Michael Faraday (1791–1867), André-Marie Ampère (1775–1836), and Georg Simon Ohm (1789-1854).

The late 19th and early 20th century produced such giants of electrical engineering as Nikola Tesla, Antonio Meucci, Thomas Edison, George Westinghouse, Werner von Siemens, Charles Steinmetz, Alexander Graham Bell and William Thomson, 1st Baron Kelvin.

Franklin Kite Plaque

Electric potential

Main article: Electric potential

The electric potential difference between two points is defined as the work done (against electrical forces) per unit of charge in moving a positive point charge slowly between two points. If one of the points is taken to be a reference point with zero potential, then the electric potential at any point can be defined in terms of the work done per unit charge in moving a positive point charge from that reference point to the point at which the potential is to be determined. For isolated charges, the reference point is usually taken to be infinity. The potential is measured in volts. (1 volt = 1 joule/coulomb) The electric potential is analogous to temperature: there is a different temperature at every point in space, and the temperature gradient indicates the direction and magnitude of the driving force behind heat flow. Similarly, there is an electric potential at every point in space, and its gradient indicates the direction and magnitude of the driving force behind charge movement.

Electric current

Main article: Current (electricity)

Nikola Tesla

An electric current is a flow of electric charge, and its intensity is measured in amperes. Examples of electric currents include metallic conduction, where electrons flow through a conductor or conductors such as a metal wire, and electrolysis, where ions (charged atoms) flow through liquids. The particles themselves often move quite slowly, while the electric field that drives them propagates at close to the speed of light. See electrical conduction for more information.

Devices that use charge flow principles in materials are called electronic devices.

A direct current (DC) is a unidirectional flow, while an alternating current (AC) reverses direction repeatedly. The time average of an alternating current is zero, but its energy capability (RMS value) is not zero.

Ohm's law is an important relationship describing the behaviour of electric currents, relating them to voltage.

For historical reasons, electric current is said to flow from the most positive part of a circuit to the most negative part. The electric current thus defined is called conventional current. It is now known that, depending on the conditions, an electric current can consist of a flow of charged particles in either direction, or even in both directions at once. The positive-to-negative convention is widely used to simplify this situation. If another definition is used - for example, "electron current" - it should be explicitly stated.

Electric field

Main article: Electric field

Michael Faraday

The concept of electric fields was introduced by Michael Faraday. The electrical field force acts between two charges, in the same way that the gravitational force acts between two masses. However, the electric field is a little bit different. Gravitational force depends on the masses of two bodies, whereas electric force depends on the electric charges of two bodies. While gravity can only pull masses together, the electric force can be an attractive or repulsive force. If both charges are of same sign (e.g. both positive), there will be a repulsive force between the two. If the charges are opposite, there will be an attractive force between the two bodies. The magnitude of the force varies inversely with the square of the distance between the two bodies, and is also proportional to the product of the unsigned magnitudes of the two charges.

Electric charge

Main article: Electric charge

Electric charge is a property of certain subatomic particles (e.g., electrons and protons) which interacts with electromagnetic fields and causes attractive and repulsive forces between them. Electric charge is a fundamental conserved property of matter and can be precisely quantified. It couples to the electromagnetic field, one of the four fundamental forces of nature.

In this sense, the phrase "quantity of electricity" is used interchangeably with the phrases "charge of electricity" and "quantity of charge". There is fundamentally only one type of electric charge, and only one variable is needed to keep track of the amount of charge.^[1] The amount of charge may be positive or negative. Through experimentation, we find that like-charged objects repel and opposite-charged objects attract one another. The magnitude of the force of attraction or repulsion is given by Coulomb's law.

See also

• Electrical engineering
• Electricity generation
• Electricity distribution
• Electricity meter
• Electrical phenomena
• Electrostatics

Safety

• Electric shock and injuries
• High-voltage hazards

Electrical phenomena in nature

• Matter: — since atoms and molecules are held together by electric forces.
• Lightning: electrical discharges in the atmosphere.
• The Earth's magnetic field — created by electric currents circulating in the planet's core.
• Sometimes due to solar flares, a phenomenon known as a power surge can be created.
• Piezoelectricity: the ability of certain crystals to generate a voltage in response to applied mechanical stress.
• Triboelectricity: electric charge taken on by contact or friction between two different materials.
• Bioelectromagnetism: electrical phenomena within living organisms; Many animals are sensitive to electric fields, some (e.g., sharks) more than others (e.g., people). Most also generate their own electric fields.
  • Gymnotiformes, such as the electric eel, deliberately generate strong fields to detect or stun their prey.
  • Neurons in the nervous system transmit information by electrical impulses known as action potentials.

References

1. ^ One Kind of Charge [1]

External links

• Energy and Electricity Information
• Tyndall: Faraday as Discovery: Identity of Electricities
• US Energy Department Statistics
• Read Congressional Research Service (CRS) Reports regarding Electricity
• Answers to several question of curious kids about electricity
• Illustrated view of how an American home's electrical system works
• How to save on your electricity bills
• Electricity around the world
• A Comprehensive Collection of Franklin’s Electrical Works: The Electrical Writings of Benjamin Franklin, Created and Collected by Robert A. Morse (2004)
• Understanding Electricity and some Electronics in 10 minutes (Steve Rose, Maui)
• Electricity Misconceptions
• Electricity and Magnetismbe-x-old:Электрычнасцьnrm:Êtricitaézh-yue:電

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Common misspelling(s) of electricity

• electricty

Dansk (Danish)
n. - elektricitet, elektricitetslære, elektrisk strøm

Nederlands (Dutch)
elektriciteit, gespannenheid, opwinding, elektriciteitsleer

Français (French)
n. - électricité, (fig) courant

Deutsch (German)
n. - Elektrizität, Strom

Ελληνική (Greek)
n. - (φυσ.) ηλεκτρισμός, ηλεκτρική ενέργεια, ηλεκτρικό ρεύμα ή φορτίο

Italiano (Italian)
elettricità, corrente

Português (Portuguese)
n. - eletricidade (f)

Русский (Russian)
электричество, электрический ток

Español (Spanish)
n. - electricidad, tensión

Svenska (Swedish)
n. - elektricitet, ström

中文（简体） (Chinese (Simplified))
电, 电学, 电流

中文（繁體） (Chinese (Traditional))
n. - 電, 電學, 電流

한국어 (Korean)
n. - 전기, 전류

日本語 (Japanese)
n. - 電気, 強い興奮

العربيه (Arabic)
‏(الاسم) كهرباء‏

עברית (Hebrew)
n. - ‮חשמל, התרגשות רבה‬

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