Electrical units | Wikipedia audio article
Electricity. Is the set of physical phenomena. Associated with, the presence, and motion of matter that has a property, of electric, charge in. Early, days electricity. Was considered, as being not related, to magnetism. Later. On many, experimental. Results, in the development, of Maxwell's, equations, indicated. That both electricity, and magnetism, are from a single phenomenon. Electromagnetism. Various. Common phenomena, are related to electricity, including. Lightning static. Electricity, electric. Heating, electric. Discharges, and many others the, presence. Of an electric charge, which can be either positive or negative produces. An electric, field the. Movement, of electric, charges, is an electric, current and produces, a magnetic field. When. A charge is placed in a location with, a nonzero electric. Field a force will act on it the. Magnitude, of this force is, given by Coulomb's law thus. If that charge were to move the electric, field would be doing work on the electric, charge, thus. We can speak of electric, potential, at a certain, point in space which is equal to the work done by an external agent, in carrying a unit of positive, charge from an arbitrarily, chosen reference. Point to that point without any acceleration, and, is typically measured in volt. Electricity. Is at the heart of many modern technologies. Being, used for. Electric. Power where electric, current is used to energize equipment. Electronics. Which deals with electrical. Circuits, that involve active electrical. Components. Such as vacuum, tubes transistors, diodes. And. Integrated circuits. And associated. Passive, interconnection technologies. Electrical. Phenomena, have been studied since antiquity, though, progress in theoretical, understanding. Remained slow until the 17th, and 18th centuries. Even. Then practical. Applications, for electricity. Were few and it would not be until the late 19th, century that electrical, engineers, were able to put it to industrial, and residential, use, the.
Rapid Expansion in electrical, technology at, this time transformed. Industry, and society becoming, a driving, force for the Second, Industrial Revolution. Electricity's. Extraordinary. Versatility. Means it can be put to an almost limitless set, of applications. Which include, transport, heating, lighting. Communications. And computation. Electrical. Power is now the backbone, of modern industrial society. Topic. History. Long, before any knowledge of electricity, existed. People were aware of shocks from electric, fish. Ancient. Egyptian, texts, dating from 20 750, BCE, referred, to these fish as the Thunderer. Of the nile and described. Him as the protectors. Of all. Other fish, electric. Fish were again reported, millennia, later by ancient Greek Roman, and Arabic naturalists. And physicians. Several. Ancient writers, such as Pliny the Elder, and scribe O'Neill Argos, attested. To the numbing effect of electric, shocks delivered by electric, catfish, and electric, rays and knew that such shocks could travel along conducting, objects. Patients. Suffering from ailments. Such as gout or headache were directed, to touch electric, fish in the hope that the powerful jolt might cure them, possibly. The earliest and, nearest approach to the discovery, of the identity, of lightning, and electricity from. Any other source is to be attributed, to the Arabs who before the 15th century had, the Arabic word for lightning rod, Road applied to the electric, ray ancient, cultures around the Mediterranean. Knew that certain objects, such as rods of amber could be rubbed with cat's fur to attract light objects, like feathers, Thales. Of Miletus made. A series, of observations on, static, electricity around, 600. BCE, from, which he believed that friction, rendered amber magnetic, in contrast, to minerals such as magnetite. Which needed, no rubbing, fails. Was incorrect, in believing the attraction, was due to a magnetic effect but later science, would prove a link between magnetism, and electricity. According. To a controversial, theory, the path ian's may have had knowledge of electroplating, based, on the 1936. Discovery, of the Baghdad battery which. Resembles, a galvanic cell though, it is uncertain whether, the artifact, was electrical, in nature. Electricity. Would remain little, more than an intellectual, curiosity, for. Millennia until 1600. When the English scientist, William Gilbert wrote de magnete in, which he made a careful study of electricity and, magnetism, distinguishing. The lodestone, effect from static, electricity produced. By rubbing amber he. Coined the new Latin word electric, as' of amber. Or, like. Amber, from. Electron-electron. The. Greek word for Amber, to. Refer to the property, of attracting, small objects. After being rubbed, this. Association. Gave rise to the English words, electric. And. Electricity. Which. Made the first appearance in print in Thomas Brown's pseudo, doxy epidemic, ER of 1646. Further work was conducted in the 17th, and early 18th centuries. By Otto von Guericke, Robert, Boyle Stephen, gray and C F du Fay later. In the 18th century Benjamin. Franklin, conducted, extensive research, in electricity, selling. His possessions, to fund his work in. June, 1750. - he is reputed to have attached, a metal key to the bottom of a dampened, kite string and flown the kite in a storm threatened. Sky a, succession. Of sparks, jumping, from the key to the back of his hand showed, that lightning was indeed electrical, in nature, he. Also explained. The apparently, paradoxical. Behavior, of the Leyden jar is a device for storing large amounts of electrical, charge in terms of electricity, consisting. Of both positive, and negative charges in. 1791. Luigi. Galvani published. His discovery of bio electromagnetics. Demonstrating. That electricity, was the medium by which neurons passed, signals, to the muscles. Alessandro. Voltas, battery, or voltaic, pile of 1800. Made from alternating, layers of zinc and copper provided. Scientists. With a more reliable source of electrical, energy than, the electrostatic. Machines previously. Used, the. Recognition, of electromagnetism. The unity, of electric, and magnetic phenomena. Is due to Hans Christian, Oersted and Andre Murray ampere in 1819.
To 1820. Michael. Faraday invented. The electric motor, in 1821. And Georg, Oh mathematically. Analyzed, the electrical, circuit, in 1827. Electricity. And magnetism, and light were, definitively, linked, by James Clerk Maxwell in particular, in his on physical. Lines of, force in. 1861. And 1862. While, the early 19th, century had, seen rapid, progress in electrical. Science the late 19th, century would, see the greatest progress, in electrical, engineering, through. Such people as Alexander. Graham Bell, Otto blury Thomas, Edison galileo, ferraris Oliver. Heaviside and, Yas Chadwick, william, thomson 1st, baron, kelvin Charles, Algernon, Parsons, Werner, von Siemens Joseph. Swan Reginald. Fessenden Nikola. Tesla and George Westinghouse. Electricity. Turned from a scientific, curiosity, into. An essential, tool for modern, life in. 1887. Heinrich, Hertz discovered. That electrodes, illuminated. With ultraviolet, light create, electric, sparks, more easily in. 1905. Albert Einstein. Published, a paper that explained, experimental. Data from, the photoelectric. Effect as, being the result of light energy being, carried, in discrete, quantized, packets, energizing. Electrons. This. Discovery, led to the quantum revolution. Einstein. Was awarded, the Nobel Prize in Physics in 1921, for. His, discovery, of the law of the photoelectric effect. The. Photoelectric. Effect is, also employed, in photo cells such as can be found in solar panels, and this is frequently, used to make electricity, commercially. The. First solid-state. Device, was the cat's. Whisker, detector, first. Used, in the 1900s. In radio receivers, a whisker. Like wire is placed lightly, in contact, with a solid crystal, such as a germanium crystal, to detect a radio signal, by the contact, Junction effect in a. Solid-state, component. The current is confined, to solid elements, and compounds engineered. Specifically, to switch and amplify, it, current. Flow can be understood, in two form, as negatively-charged, electrons and, as positively, charged, electron, deficiencies, called holes, these. Charges, and holes are understood, in terms of quantum, physics the. Building, material, is most often a crystalline, semiconductor the. Solid-state device came into its own with the invention of the transistor in. 1947. Common. Solid-state, devices, include, transistors. Microprocessor. Chips and RAM a, specialized. Type of Ram called flash Ram is used in USB, flash drives and more recently, solid-state. Drives to replace mechanically. Rotating, magnetic disk hard disk drives. Solid-state. Devices. Became, prevalent in the 1950s. And the 1960s, during. The transition, from vacuum tubes to semiconductor. Diodes transistors. Integrated. Circuit, IC and, the light emitting, diode led. Topic. Concepts. Topic. Electric. Charge. The. Presence, of charge gives, rise to an, electrostatic, force. Charges. Exert a force on each other an effect that was known though not understood, in antiquity. A lightweight. Ball suspended from a string can be charged, by touching it with a glass rod that has itself been charged, by rubbing with a cloth if. A, similar ball is charged by the same glass rod it is found to repel the first the charge acts to force the two balls apart, two. Balls that are charged, with a rubbed amber rod also repel, each other, however. If one ball is charged by the glass rod and the other by an amber rod the two balls are found to attract each other, these. Phenomena. Were investigated. In the late 18th, century by charles-augustin. De, Coulomb who deduced that charge manifests. Itself in two opposing forms, this. Discovery, led to the well-known axiom. Light charged, objects, repel and opposite charged, objects, attract the force acts on the charged particles, themselves, hence charge has a tendency, to spread itself as evenly as possible over a conducting, surface, the. Magnitude, of the electromagnetic. Force whether, attractive, or repulsive is, given by Coulomb's law which, relates the force to the product of the charges and, has an inverse square relation. To the distance, between em the. Electromagnetic. Force is very strong second. Only in strength, to the strong interaction. But unlike that force it operates, over all distances, in. Comparison. With the much weaker gravitational, force, the electromagnetic. Force, pushing, two electrons, apart is 1042. Times that of the gravitational, attraction pulling. Them together study. Has shown that the origin, of charges, from certain, types of subatomic particles. Which have the property of electric, charge.
Electric. Charge gives rise to and, interacts, with the electromagnetic. Force, one of the four fundamental forces. Of nature the. Most familiar carriers. Of electrical, charge of the electron, and proton. Experiment. Has shown charge to be a conserved, quantity that. Is the net charge within an electrically, isolated, system, will always remain constant regardless. Of any changes, taking place within, that system, within. The system, charge, may be transferred, between bodies, either by direct, contact or, by passing along a conducting. Material such. As a wire the. Informal, term static, electricity, refers. To the net presence, or imbalance. Of charge on a body usually, caused when dissimilar, materials, are rubbed together transferring. Charge from one to the other, the. Charge on electrons, and protons is, opposite in sign hence, an amount of charge may be expressed, as being either negative, or positive, by. Convention. The charge carried, by electrons is. Deemed negative, and that by protons, positive a custom, that originated, with the work of Benjamin, Franklin, the amount. Of charge is usually, given the symbol Q and expressed, in coulombs each electron, carries, the same charge of approximately. Minus one point six oh two two times, ten minus 19, coulomb, the. Proton, has a charge that is equal and opposite and thus plus one point six oh two two times, ten minus 19, coulomb. Charges. Possess not just by matter but, also by antimatter, each antiparticle. Bearing an equal and opposite charge to its corresponding particle. Charge, can be measured by a number of means an early instrument. Being the goldleaf electroscope, which, although still in use for classroom, demonstrations. Has been superseded, by the electronic. Electrometer. Topic. Electric. Current. The, movement, of electric, charge is known as an electric, current the intensity, of which is usually, measured in amperes current, can. Consist of any moving charged particles most commonly, these are electrons, but any charge in motion, constitutes. A current. Electric. Current can flow through some, things, electrical, conductors, but will not flow through an electrical, insulator by, historical, convention. A positive, current is defined as having the same direction of flow as any positive, charge it contains, or to flow from the most positive part, of a circuit, to the most negative part, current. Defined in this manner is, called conventional, current the. Motion, of negatively, charged, electrons, around an electric, circuit one of the most familiar forms, of current is the steam positive, in the opposite direction to, that of the electrons. However. 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. The. Process, by which electric. Current passes, through a material is termed electrical, conduction and its nature varies, with that of the charged particles and, the material, through which they are traveling. Examples. Of electric, currents, include metallic, conduction, where electrons, flow through a conductor, such as metal and electrolysis. Where, ions charged, atoms flow, through liquids or through plasmas, such as electrical, sparks, while. The particles, themselves can, move quite slowly sometimes. With an average drift, velocity, only fractions. Of a millimeter per second, the electric, field that drives them itself propagates, at close to the speed of light enabling. Electrical. Signals, to pass rapidly, along wires current. Causes several observable. Effects, which historically, were the means of recognizing. Its presence, that. Water could be decomposed by, the current, from a voltaic pile was discovered, by Nicholson, and Carlisle, in 1800. A process, now known as electrolysis. Their. Work was greatly expanded, upon by Michael Faraday in 1833. Current. Through a resistance, causes, low heating. An effect James Prescott Joule studied. Mathematically. In 1840. One. Of the most important, discoveries, relating, to current was made accidentally. By Hans Christian Oersted in 1820. When while, preparing, a lecture he, witnessed the current in a wire disturbing. The needle of a magnetic compass, he. Had discovered, electromagnetism. A fundamental. Interaction, between electricity, and magnetics. The. Level of electromagnetic, emissions, generated. By electric, arcing is high enough to produce electromagnetic. Interference. Which can be detrimental to, the workings, of adjacent, equipment, in engineering, or household, applications. Current, is often described, as being either direct, current, DC or, alternating, current, AC, these.
Terms, Refer to how the current, varies in time direct. Current, is produced by example, from a battery and required by most electronic. Devices is a unidirectional. Flow from the positive part of a circuit, to the negative, if, as, is most common, this flow is carried by electrons they. Will be traveling in the opposite direction. Alternating. Current is any current, that reverses, direction, repeatedly, almost, always this takes the form of a sine wave. Alternating. Current thus, pulses, back and forth within a conductor, without the charge moving any net distance, over time, the. Time averaged, value, of an alternating, current is, zero but it delivers energy, in first one direction. And then the reverse. Alternating. Current is affected, by electrical, properties, that are not observed, under steady state direct. Current, such as inductance, and capacitance. These. Properties, however can, become important, when circuitry. Is subjected, to transients, such as when first energized. Topic. Electric. Field. The. Concept, of the electric, field was introduced, by Michael Faraday an electric. Field is created by, a charged, body in the space that surrounds it, and results, in a force exerted on any other charges, placed within the field the. Electric, field acts between, two charges, in a similar manner to the way that the gravitational. Field acts between two masses, and like it extends, towards infinity, and chose an inverse-square relationship. With distance. However. There, is an important, difference, gravity. Always acts in attraction, drawing two masses, together while, the electric, field can result in either attraction. Or repulsion. Since. Large bodies, such as planets generally, carry no net charge the, electric, field at a distance is, usually, zero thus. Gravity, is the dominant, force at distance, in the universe, despite, being much weaker, an. Electric. Field generally, varies, in space and, its strengths at any one point is defined as the force per unit charge that, would be felt by a stationary, negligible. Charge if placed at that point, the. Conceptual. Charge termed, the test charge must, be vanishingly, small to, prevent its own electric, field disturbing, the main field and must also be stationary, to prevent the effect of magnetic fields. As the. Electric, field is defined in terms of force and forces, a vector, so it follows that an electric, field is also a vector having both magnitude, and direction. Specifically. It is a vector field the study of electric, fields, created, by stationary, charges, is called electrostatics. The. Field may be visualized.
By A set of imaginary, lines whose direction, at any point is the same as that of the field, this. Concept, was introduced, by faraday whose term lines, of force still, sometimes sees, use, the. Field lines are the paths that a point positive, charge would seek to make as it was forced to move within the field they are however an imaginary, concept with no physical existence and, the field permeates, all the intervening space between, the lines, field. Lines, emanating from, stationary, charges. Have several, key properties, first, that they originate, at positive, charges and terminate, at negative, charges second. That they must enter any good conductor, at right angles and third that they may never cross nor close in on themselves a hollow conducting. Body carries, all its charge on its outer surface. The. Field is therefore, zero at all places inside the body this, is the operating, principle, of the Faraday cage a conducting. Metal shell which isolates, its interior from outside, electrical, effects. The. Principles, of electrostatics. Are important, when designing items, of high voltage equipment. There. Is a finite, limit to the electric, field strength that, may be withstood by any medium. Beyond. This point electrical. Breakdown occurs, in an electric, arc causes, flashover, between, the charged parts, air. For, example tends. To arc across small gaps at electric, field strengths, which exceed 30 kilo, volts per centimeter over. Larger. Gaps, it's breakdown, strength is weaker, perhaps, one kilo, volt per centimeter, the. Most visible natural, occurrence, of this is lightning caused, when charge becomes separated. In the clouds by rising columns, of air and raises, the electric, field in the air to greater than it can withstand, the. Voltage, of a large lightning, cloud may be as high as 100. Mega volts, and have discharge, energies, as great as 250. Kilo, watt hours, the field strength is greatly affected, by nearby, conducting. Objects, and it is particularly, intense, when it is forced to curve around sharply. Pointed objects. This. Principle, is exploited, in the Lightning conductor, the sharp spike of which acts to encourage, the lightning stroke to develop there rather than to the building it serves to protect. Topic. Electric. Potential. The, concept, of electric, potential is closely linked, to that of the electric field, a small. Charge placed within an electric, field experiences. A force and to have brought that charge to that point against the force requires, work, the. Electric, potential, at any point is defined as the energy required to bring a unit test charge from an infinite distance slowly, to that point it. Is usually, measured in volts and one volt is the potential, for which one Joule of work must, be expended to bring a charge of one Coulomb from infinity, this. Definition, of potential, while formal, has little practical application. And the more useful concept, is that of electric, potential difference and, is the energy required to move a unit charge, between two specified, points, an, electric. Field has the special property that it is conservative, which, means that the path taken, by the test charge is irrelevant all paths, between two specified, points, expend the same energy and thus a unique, value for potential. Difference, may be stated, the. Volt is so strongly identified. As the unit of choice for measurement, and description, of electric, potential, difference that, the term voltage, sees greater everyday, usage. For. Practical, purposes, it is useful to define a common reference point to which potentials. May be expressed, and compared, while. This could be at infinity a much more useful reference. Is the earth itself which is assumed to be at the same potential everywhere, this. Reference point naturally. Takes the name earth or ground earth. Is assumed to be an infinite source of equal amounts of positive and negative charge and is therefore electrically. Uncharged, and uncharged. Abul electric, potential, is a scalar quantity that, is it has only magnitude, and not Direction, it. May be viewed, as analogous to height just, as a released object, will fall through a difference, in Heights caused, by a gravitational. Field so, a charge will fall across the voltage caused by an electric, field as, relief. Maps show contour, lines marking, points of equal height a set of lines marking, points of equal potential, known, as equipotentials, may, be drawn around an electro, statically, charged, object. The, equipotentials, cross, all lines of force at right angles, they, must also like Errol L to a conductors, surface, otherwise this would produce a force that will move the charge carriers, to even the potential of the surface. The. Electric, field was formally, defined as the force exerted per unit charge but, the concept, of potential, allows for a more useful and equivalent, definition, the electric, field is the local gradient, of the electric potential.
Usually. Expressed, in volts per meter the, vector direction, of the field is the line of greatest slope, of potential, and where the equipotentials, like closest, together. Topic. Electromagnets. A studs, discovery, in 1821. That, a magnetic field existed. Around all sides of a wire carrying, an electric current indicated. That there was a direct relationship between, electricity. And magnetism. Moreover. The interaction. Seemed different from gravitational, and electrostatic. Forces the two forces of nature then known the. Force on the compass needle did, not direct, it tore away from the current carrying wire but, acted at right angles, to it, stirred. Slightly, obscure, words were that the, electric, conflict, acts in a revolving, manner the. Force also depended. On the direction of the current through if the flow was reversed then the force did to Oersted did not fully understand, his discovery, but he observed the effect was reciprocal, a current, exerts, a force on a magnet, and a magnetic field exerts, a force on a current, the. Phenomenon, was further investigated. By ampair who discovered, that two parallel, current-carrying, wires, exerted. A force upon, each other, two wires conducting. Currents, in the same direction are, attracted, to each other while wires containing. Currents, in opposite, directions are, forced apart, the. Interaction. Is mediated, by the magnetic, field each current, produces, and forms the basis, for the International, definition, of the ampere. This. Relationship. Between magnetic, fields, and currents, is extremely, important, for it led to Michael Faraday's, invention, of the electric motor in 1821. Faraday's. Homopolar, motor consisted. Of a permanent magnet, sitting in a pool of mercury a, current. Was allowed through a wire suspended from, a pivot above the magnet and dipped into the mercury, the. Magnet, exerted, a tangential, force on the wire making. It circle around the magnet for as long as the current was maintained. Experimentation. By Faraday, in 1831. Revealed, that a wire moving, perpendicular, to a magnetic field developed, a potential, difference between its ends, further. Analysis. Of this process, known, as electromagnetic, induction. Enabled. Him to state the principle now, known as Faraday's, law of induction that, the potential difference induced. In a closed circuit, is proportional, to the rate of change of magna took flux through the loop. Exploitation. Of this discovery enabled, him to invent the first electrical.
Generator, In 1831. In which he converted the, mechanical, energy of a rotating copper disc to electrical, energy, Faraday's. Disk was inefficient and of no use as a practical, generator, but, it showed the possibility of generating, electric, power using, magnetism, a possibility. That would be taken up by those that followed on from his work. Topic. Electrochemistry. The, ability, of chemical, reactions, to produce electricity, and, conversely, the ability, of electricity, to drive chemical, reactions, has a wide array of uses. Electrochemistry. Has always been an important, part of electricity. From, the initial invention, of the voltaic pile. Electrochemical. Cells have evolved into the many different, types of batteries, electroplating. And electrolysis, cells. Aluminium. Is produced, in vast quantities this, way and many portable, devices are electrically, powered using rechargeable cells. Topic. Electric. Circuits. An electric. Circuit is an interconnection, of electric, components, such that electric, charge is made to flow along a closed path a circuit, usually, to perform some useful, task, the. Components. In an electric, circuit can, take many forms which, can include elements, such as resistors, capacitors. Switches. Transformers. And electronics. Electronic. Circuits, contain, active components. Usually, semiconductors. And typically, exhibit nonlinear. Behavior requiring. Complex, analysis. The. Simplest, electric, components. Are those that are termed passive, and linear while they may temporarily, store, energy they contain no sources, of it and exhibit, linear responses, to stimuli the resistor, is perhaps the simplest of passive, circuit, elements, as its name suggests it, resists, the current through it dissipating. Its energy as heat the. Resistance, is a consequence, of the motion of charge through a conductor, in metals, for, example resistance. Is primarily, due to collisions, between electrons and. Ions, Ohm's. Law is, a basic, law of circuit, theory stating. That the current passing, through a resistance, is directly proportional. To the potential difference across it, the. Resistance of most materials. Is relatively, constant over a range of temperatures, and currents, materials. Under these conditions, are known as ohmic, the. Ohm the unit of resistance was. Named in honor of Georg ohm and is symbolized by the Greek letter Omega one. Ohm is the resistance, that will produce a potential, difference of one volt in, response, to a current of 1 amp the capacitor, is a development.
Of The Leyden jar and is a device that can store charge and thereby storing, electrical, energy in the resulting, field it. Consists. Of two conducting, plates separated, by, a thin insulating. Dielectric. Layer in practice, thin metal foils are coiled together increasing. The surface area, per unit volume and, therefore the capacitance. The. Unit of capacitance, is the farad named after Michael Faraday, and given the symbol F 1 farad, is the capacitance, that develops, a potential, difference of one volt when, it stores a charge of one Coulomb. A capacitor, connected to a voltage supply initially. Causes, a current as it accumulates, charged this current will however decay, in time as the capacitor, fills eventually. Falling to zero a. Capacitor. Will therefore not permit a steady state current but, instead blocks it the inductor, is a conductor. Usually, a coil of wire that stores energy in a magnetic field in response, to the current through it when. The current changes, the magnetic, field does to inducing. A voltage, between the ends of the conductor, the. Induced, voltage is, proportional to the time rate of change of the current, the. Constant, of proportionality is. Termed the inductance, the. Unit of inductance is. The Henry named, after Joseph Henry, a contemporary. Of Faraday, 1. Henry is the inductance, that will induce a potential, difference of one volt if the current through it changes, at a rate of 1 ampere per second, the. Inductors, behavior, is in some regards, converse, to that of the capacitor, it will freely allow an unchanging, current but opposes, our rapidly changing one. Topic. Electric. Power. Electric. Power is the rate at which electric. Energy is transferred, by an electric, circuit, the. SI unit of power is the watt one Joule per second. Electric. Power like, mechanical, power is the rate of doing work measured. In watts and represented. By the letter P the term wattage, is used colloquially to, mean electric, power in watts, the. Electric, power in watts produced, by an electric, current I consisting, of a charge of Q coulombs, every, T seconds, passing, through an electric, potential, voltage difference, of V is, P. Equals. Work done per unit time. Equals. Q. V. T. Equals I. V. Display. Style P equals, text work done per unit time equals, track QV, t equals, I V where. Q. Is electric, charge in coulombs. T. Is time in seconds, I is. Electric, current in amperes. V. Is electric, potential, or voltage in, volts electricity. Generation, is often done with electric, generators, but can also be supplied by chemical, sources, such as electric, batteries, or by other means from a wide variety of sources of energy. Electric. Power is generally, supplied to businesses, and homes by the electric, power industry. Electricity. Is usually, sold by the kilowatt, hour 3.6, mega joules which is the product of power in kilowatts multiplied. By running time in hours. Electric. Utilities, measure power using, electricity, meters, which keep a running total of the electric, energy delivered. To a customer. Unlike. Fossil fuels, electricity. Is a low entropy form of energy and can be converted into motion or many other forms, of energy with high efficiency. Topic. Electronics. Electronics. Deals with electrical, circuits, that involve active electrical.
Components. Such as vacuum, tubes transistors, diodes. Optoelectronics. Sensors. And integrated, circuits and associated. Passive, interconnection technologies. The. Nonlinear, behavior of, active components. And their ability, to control, electron, flows makes amplification. Of weak signals, possible, in electronics. Is widely used in information, processing. Telecommunications. And signal, processing, the. Ability, of electronic, devices to act as switches makes, digital information, processing, possible. Interconnection. Technologies such. As circuit, boards electronics. Packaging, technology, and other varied, forms of communication. Infrastructure, complete, circuit, functionality. And transform, the mixed components, into a regular, working system. Today. Most, electronic. Devices use, semiconductor. Components to, perform electron. Control, the. Study of semiconductor. Devices and, related technology, is considered, a branch of solid-state physics. Whereas the design and construction of, electronic, circuits, to solve practical problems come. Under Electronics, Engineering. Topic. Electromagnetic. Wave. Faraday's. And amperes work showed that a time-varying magnetic, field. Acted, as a source of an electric, field and a time varying, electric field, was a source of a magnetic field, thus. When either field is changing in, time then, a field of the other is necessarily, induced. Such. A phenomenon. Has the properties, of a wave and is naturally, referred to as an electromagnetic. Wave. Electromagnetic. Waves were analyzed theoretically. By James Clerk Maxwell in, 1864. Maxwell. Developed, a set of equations, that could unambiguously. Describe, the interrelationship. Between electric. Field magnetic. Field, electric. Charge and electric, current he. Could moreover, prove that such a wave would necessarily travel at the speed of light and thus light itself, was a form of electromagnetic. Radiation. Maxwell's. Laws which. Unify, light fields. And charge are one of the great milestones, of theoretical, physics thus, the work of many researchers, enabled, the use of electronics, to convert, signals into, high frequency. Oscillating, currents. And via suitably, shaped conductors. Electricity. Permits the transmission. And reception of, these signals, via radio waves over very long distances. Topic. Production. And users. Topic. Generation. And transmission. In the, 6th century BC, the Greek philosopher, Thales of Miletus, experimented. With amber rods and these experiments. Were the first studies, into the production, of electrical, energy, while.
This Method now known as the triboelectric effect, can, lift light objects, and generate sparks it is extremely, inefficient, it. Was not until the invention of the voltaic pile. In the 18th century that a viable source, of electricity, became available the, voltaic. Pile, and it's modern descendant, the electrical, battery store, energy chemically. And make it available on, demand in the form of electrical, energy, the. Battery is a versatile. And very common, power source, which is ideally, suited to many applications. But its energy storage, is finite, and once discharged, it must be disposed, of or recharged. For. Large electrical. Demands, electrical, energy must be generated, and transmitted, continuously over. Conductive, transmission. Lines. Electrical. Power is usually generated, by electromechanical. Generators. Driven by steam produced, from fossil fuel combustion, or the heat released from nuclear, reactions, or from other sources such as kinetic, energy extracted, from wind or flowing water, the modern. Steam turbine, invented, by Sir Charles Parsons, in, 1884. Today generates, about 80 percent, of the electric, power in the world using, a variety of heat sources. Such. Generators, bear, no resemblance to, Faraday's, homopolar, disc generator, of 1831. But they still rely on his electromagnetic. Principle, that a conductor linking, a changing, magnetic field, induces, a potential, difference across its ends, the. Invention, in the late 19th, century of, the transformer. And that electrical, power could be transmitted, more efficiently, at a higher voltage but, lower current. Efficient. Electrical, transmission meant, in turn that electricity, could be generated, at centralized, power stations. Where it benefited from economies, of scale, and then be dispatched relatively. Long distances to. Where it was needed. Since. Electrical. Energy cannot easily be stored in quantities, large enough to meet demands on a national, scale at all times exactly. As much must be produced, as is required, this. Requires, electricity, utilities. To make careful, predictions, of their electrical, loads and maintain, constant, coordination. With their power stations. A certain. Amount of generation, must, always be held in reserve to cushion an electrical, grid against inevitable, disturbances. And losses. Demand. For electricity, grows, with great rapidity as, a nation, modernizes, and its economy develops. The. United, States showed a 12%, increase in demand during each year of the first three decades of the 20th, century a rate of growth that is now being experienced. By emerging, economies, such as those of India or China. Historically. The growth rate for electricity, demand has outstripped, that for other forms of energy, environmental. Concerns with electricity generation. Have, led to an increased, focus on generation, from renewable, sources in, particular from, wind and hydro power while. Debate can be expected, to continue over the environmental. Impact of different means of electricity, production, its, final, form is relatively, clean.
Topic. Applications. Electricity. Is a very convenient, way to transfer. Energy and it has been adapted to a huge, and growing number. Of uses, the. Invention, of a practical, incandescent lightbulb. In the 1870s. Led to lighting, becoming, one of the first publicly, available applications. Of electrical, power, although. Electrification, brought. With it its own dangers, replacing. The naked flames of gas lighting greatly. Reduced fire hazards, within homes and factories. Public. Utilities, were set up in many cities targeting. The burgeoning market for electrical, lighting in the. Late 20th, century and, in modern times the trend has started, to flow in the direction of deregulation. In the electrical, power sector, the resistive, Joule heating effect, employed, in filament, lightbulbs, also sees more direct use in electric, heating, while. This is versatile, and controllable, it can be seen as wasteful, since, most electrical, generation, has already required, the production of heat at a power station a number. Of countries such as Denmark have. Issued legislation. Restricting or banning the use of resistive. Electric, heating, in new buildings. Electricity. Is however still a highly practical, energy, source for heating and refrigeration with. Air-conditioning heat, pumps representing. A growing sector for electricity, demand for heating and cooling the effects, of which electricity. Utilities, are increasingly, obliged, to accommodate, electricity. Is used within, telecommunications. And indeed, the electrical, Telegraph, demonstrated. Commercially, in 1837. By Cooke, and Wheatstone was. One of its earliest applications. With. The construction, of first intercontinental. And then transatlantic, Telegraph. Systems in the 1860s. Electricity. Had enabled communications. In minutes across the globe. Optical. Fiber and satellite, communication. Have taken a share of the market for, communication. Systems, but electricity, can be expected, to remain an essential, part of the process. The. Effects, of electromagnetism. Are most visibly, employed, in the electric, motor which, provides a clean and efficient, means of motivepower a, stationary. Motor such, as a winch is easily provided, with a supply of power but a motor that moves with its application such. As an electric, vehicle is obliged, to either carry along a power source such as a battery or, to collect current, from a sliding, contact such, as a pantograph. Electrically. Powered vehicles, are used in public transportation, such. As electric, buses and trains and an increasing, number of battery-powered, electric. Cars in private, ownership. Electronic. Devices make, use of the transistor, perhaps, one of the most important, inventions of the 20th century, and a fundamental building block, of all modern circuitry. A modern. Integrated, circuit, may contain, several billion, miniaturized, transistors. In a region only a few centimetres, square. You. Topic. Electricity. In the natural, world. Topic. Physiological. Effects. A voltage. Applied to a human, body causes, an electric current through the tissues, and although the relationship, is nonlinear, the greater the voltage, the greater the current, the.
Threshold, For perception varies. With the supply frequency and, with the path of the current but is about 0.1. Milli amperes, to 1 milliampere for mains frequency electricity. Though, a current, as low as a micro, amp can be detected as an electro, vibration, effect under certain conditions. If the. Current is sufficiently, high it will cause muscle contraction. Fibrillations, of the heart and tissue bands, the. Lack of any visible, sign that a conductor is electrified, makes electricity, a particular, hazard, the. Pain caused by an electric, shock can be intense bleeding, electricity. At times to be employed as a method of torture, death. Caused by an electric, shock is referred to as electrocution. Electrocution. Is still the means of judicial, execution. In some jurisdictions though. Its use has become rarer, in recent, times. Topic. Electrical. Phenomena, in nature. Electricity. Is not a human invention and may be observed, in several forms, in nature, a prominent, manifestation. Of which is lightning, many. Interactions, familiar. At the macroscopic level such. As touch friction, or chemical, bonding are due to interactions. Between electric. Fields, on the atomic scale, the. Earth's magnetic. Field is thought to arise from a natural, dynamo, of circulating, currents, in the planets core, certain. Crystals, such as quartz, or even sugar generate, a potential, difference across the phases when subjected to external, pressure, this. Phenomenon, is known as piezoelectricity. From. The Greek PI's aim peers a meaning, to press and was discovered, in 1880, by Pierre, and Jacques Curie, the. Effect is reciprocal. And when a piezoelectric, material is subjected, to an electric field a small change in physical dimensions. Takes place section. Bioelectric. Genesis in microbial, life is a prominent phenomenon, in soils, and sediment, ecology, resulting, from anaerobic respiration. The. Microbial. Fuel cell, mimics, this ubiquitous, natural. Phenomenon. Some. Organisms, such as sharks, are able to detect and respond to changes, in electric, fields, an ability known as electroreception, while, others termed electrogenic, are able to generate voltages. Themselves, to serve as a predatory, or defensive, weapon the. Order Jim motor forms, of which the best-known example, is the electric, eel detect, or stun their prey via, high voltages, generated. From modified, muscle, cells called electrocytes, all. Animals. Transmit, information along, the cell membranes, with voltage, pulses, called action, potentials, whose functions, include communication. By the nervous system between neurons, and muscles an, electric. Shock stimulates. This system, and causes, muscles, to contract. Action. Potentials, are also responsible, for coordinating, activities, in certain, plants. Topic. Cultural. Perception. In, 1850. William, Gladstone asked. The scientist, Michael, Faraday why, electricity. Was valuable. Faraday. Answered, one day sir, you may tax it in the 19th, and early 20th century. Electricity. Was not part of the everyday life of many people even, in the industrialized. Western world, the. Popular, culture, of the time accordingly, often, depicted, it as a mysterious, quasi, magical, force that can say the living revive, the dead or otherwise bend the laws of nature, this. Attitude, began with the 1771. Experiments. Of Luigi, Galvani in, which the legs of dead frogs were shown to twitch on application, of animal electricity. Revitalization. Or, resuscitation. Of apparently, dead or drowned persons, was reported, in the medical literature shortly. After Galvani's, work, these. Results, were known to Mary Shelley when she authored Frankenstein. 1819. Although, she does not name the method of revitalization, of the monster, the. Revitalization. Of monsters, with electricity, later, became, a stock theme in horror films as, the. Public familiarity. With electricity, as the lifeblood of the Second Industrial Revolution, grew. Its wielders, were more often cast in a positive, light such, as the workers, who finger. Death at the gloves end as they peace and repeats the living wires in. Rudyard. Kipling's, 1907. Poem sons of martha, electrically. Powered vehicles. Of every sort featured, large in adventure, stories, such as those of Jules Verne and the Tom Swift books, the. Masters of electricity. Whether fictional, or real, including. Scientists. Such as Thomas Edison Charles. Steinmetz, or Nikola Tesla, were, popularly, conceived, of as having wizard-like powers, with electricity, ceasing. To be a novelty and becoming a necessity of everyday life in the later half of the 20th century.
It Required, particular, attention. By popular, culture only, when it stops flowing an event that usually, signals, disaster. The. People who keep it flowing such as the nameless hero of Jimmy Webb's song Wichita. Lineman. 1968. Are still often cast as heroic, wizard, like. You. Topic. See, also. Ampère's. Circuital law, connects. The direction, of an electric, current and its associated, magnetic. Currents. Electric. Potential energy the, potential energy of a system of charges. Electricity. Markets the sale of electrical. Energy. Hydraulic. Analogy, an analogy, between the flow of water and electric, current. Equals. Equals notes.