1.
Electrostatic generator
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An electrostatic generator, or electrostatic machine, is an electromechanical generator that produces static electricity, or electricity at high voltage and low continuous current. Electrostatic generators operate by using manual power to mechanical work into electric energy. The charge is generated by one of two methods, either the effect or electrostatic induction. Electrostatic machines are used in science classrooms to safely demonstrate electrical forces. Electrostatic generators such as the Van de Graaff generator, and variations as the Pelletron, a primitive form of frictional machine was invented around 1663 by Otto von Guericke, using a sulphur globe that could be rotated and rubbed by hand. It may not actually have been rotated during use and was not intended to produce electricity, isaac Newton suggested the use of a glass globe instead of a sulphur one. Francis Hauksbee improved the design, with his frictional electrical machine that enabled a glass sphere to be rotated rapidly against a woollen cloth. Generators were further advanced when Prof. Georg Matthias Bose of Wittenberg added a collecting conductor. Bose was the first to employ the prime conductor in such machines, in 1746, William Watsons machine had a large wheel turning several glass globes, with a sword and a gun barrel suspended from silk cords for its prime conductors. Johann Heinrich Winckler, professor of physics at Leipzig, substituted a leather cushion for the hand, during 1746, Jan Ingenhousz invented electric machines made of plate glass. In 1768, Jesse Ramsden constructed a widely used version of an electrical generator. In 1783, Dutch scientist Martin van Marum of Haarlem designed a large electrostatic machine of high quality with glass disks 1.65 meters in diameter for his experiments. Capable of producing voltage with either polarity, it was built under his supervision by John Cuthbertson of Amsterdam the following year, the generator is currently on display at the Teylers Museum in Haarlem. In 1785, N. Rouland constructed a machine that rubbed two grounded tubes covered with hare fur. The Winter machine possessed higher efficiency than earlier friction machines, in the 1830s, Georg Ohm possessed a machine similar to the Van Marum machine for his research. In 1840, the Woodward machine was developed by improving the Ramsden machine, also in 1840, the Armstrong hydroelectric machine was developed, using steam as a charge carrier. The presence of charge imbalance means that the objects will exhibit attractive or repulsive forces. Rubbing two non-conductive objects generates a great amount of static electricity and this is not the result of friction, two non-conductive surfaces can become charged by just being placed one on top of the other
2.
Nuclear Regulatory Commission
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The Nuclear Regulatory Commission is an independent agency of the United States government tasked with protecting public health and safety related to nuclear energy. Established by the Energy Reorganization Act of 1974, the NRC began operations on January 19,1975 as one of two agencies to the United States Atomic Energy Commission. Prior to 1975 the Atomic Energy Commission was in charge of matters regarding radionuclides, the AEC was dissolved, because it was perceived as unduly favoring the industry it was charged with regulating. The NRC was formed as an independent commission to oversee nuclear energy matters, oversight of nuclear medicine, the U. S. AEC became the Energy Research and Development Administration in 1975, responsible for development and oversight of nuclear weapons. In 1977, ERDA became the United States Department of Energy, in 2000, the National Nuclear Security Administration was created as a subcomponent of DOE, responsible for nuclear weapons. Has, in critical areas, abdicated its role as a regulator altogether. To cite three examples, A1986 Congressional report found that NRC staff had provided valuable assistance to the utility seeking an operating license for the controversial Seabrook plant. The origins and development of NRC regulatory processes and policies are explained in five volumes of published by the University of California Press. These are, Controlling the Atom, The Beginnings of Nuclear Regulation 1946–1962, containing the Atom, Nuclear Regulation in a Changing Environment, 1963–1971. The NRC has produced a booklet, A Short History of Nuclear Regulation 1946–2009. Thomas Wellock, an academic, is the NRC historian. Before joining the NRC, Wellock wrote Critical Masses, Opposition to Nuclear Power in California, the NRC is headed by five Commissioners appointed by the President of the United States and confirmed by the United States Senate for five-year terms. One of them is designated by the President to be the Chairman, the current chairman is Kristine Svinicki. President Donald Trump designated Ms. Svinicki as Chairman of the NRC effective Jan, the NRC consists of the Commission on the one hand and offices of the Executive Director for Operations on the other. The Commission is divided into two committees and one Board, the Atomic Safety and Licensing Board Panel, as well as 8 commission staff offices, of these operations offices, NRCs major program components are the first five offices mentioned above. NRCs proposed FY2015 budget is $1,059.5 million and this is an increase of $3.6 million, including 65.1 FTE, compared to FY2014. NRC headquarters offices are located in unincorporated North Bethesda, Maryland, region I, located in King of Prussia, Pennsylvania, oversees the northeastern states. Region II, located in Atlanta, Georgia, oversees most of the southeastern states, region III, located in Lisle, Illinois, oversees the Midwest
3.
Electricity generation
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Electricity generation is the process of generating electric power from sources of primary energy. For electric utilities, it is the first process in the delivery of electricity to consumers, the other processes as transmission, distribution, energy storage and recovery using pumped-storage methods are normally carried out by the electric power industry. Other energy sources include solar photovoltaics and geothermal power, the fundamental principles of electricity generation were discovered during the 1820s and early 1830s by the British scientist Michael Faraday. This method is used today, electricity is generated by the movement of a loop of wire. Central power stations became practical with the development of alternating current power transmission, using power transformers to transmit power at high voltage. Electricity has been generated at central stations since 1882, the use of power-lines and power-poles have been significantly important in the distribution of electricity. There are seven fundamental methods of transforming other forms of energy into electrical energy. Static electricity, form the physical separation and transport of charge and it was the first form discovered and investigated, and the electrostatic generator is still used even in modern devices such as the Van de Graaff generator and MHD generators. In Electromagnetic induction, a generator, dynamo or alternator transforms kinetic energy into electricity. This is the most used form for generating electricity and is based on Faradays law and it can be experimented by rotating a magnet within closed loops of a conducting material. Almost all commercial electrical generation is done using electromagnetic induction, in mechanical energy forces a generator to rotate. Almost all electrical power on Earth is generated with a turbine, driven by wind, water, there are many different methods of developing mechanical energy, including heat engines, hydro, wind and tidal power. Most electric generation is driven by heat engines, the combustion of fossil fuels supplies most of the heat to these engines, with a significant fraction from nuclear fission and some from renewable sources. The modern steam turbine currently generates about 80% of the power in the world using a variety of heat sources. Power sources include, Steam Water is boiled by coal burned in a power plant. Nuclear fission heat created in a nuclear reactor creates steam, less than 15% of electricity is generated this way. Natural gas, turbines are directly by gases produced by combustion. Combined cycle are driven by steam and natural gas
4.
Mechanical energy
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In the physical sciences, mechanical energy is the sum of potential energy and kinetic energy. It is the associated with the motion and position of an object. The principle of conservation of energy states that in an isolated system that is only subject to conservative forces the mechanical energy is constant. In elastic collisions, the energy is conserved but in inelastic collisions. The equivalence between lost mechanical energy and an increase in temperature was discovered by James Prescott Joule and it is defined as the objects ability to do work and is increased as the object is moved in the opposite direction of the direction of the force. On the contrary, when a force acts upon an object. Though energy cannot be created or destroyed in an isolated system, the pendulum reaches greatest kinetic energy and least potential energy when in the vertical position, because it will have the greatest speed and be nearest the Earth at this point. On the other hand, it will have its least kinetic energy and greatest potential energy at the positions of its swing. However, when taking the forces into account, the system loses mechanical energy with each swing because of the work done by the pendulum to oppose these non-conservative forces. This equivalence between mechanical energy and heat is especially important when considering colliding objects, in an elastic collision, mechanical energy is conserved – the sum of the mechanical energies of the colliding objects is the same before and after the collision. After an inelastic collision, however, the energy of the system will have changed. Usually, the energy before the collision is greater than the mechanical energy after the collision. In inelastic collisions, some of the energy of the colliding objects is transformed into kinetic energy of the constituent particles. This increase in energy of the constituent particles is perceived as an increase in temperature. The collision can be described by saying some of the energy of the colliding objects has been converted into an equal amount of heat. Thus, the energy of the system remains unchanged though the mechanical energy of the system has reduced. A satellite of mass m at a distance r from the centre of Earth possesses both kinetic energy, K, and gravitational energy, U. These devices can be placed in categories, An electric motor converts electrical energy into mechanical energy
5.
Electric power
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Electric power is the rate, per unit time, at which electrical energy is transferred by an electric circuit. The SI unit of power is the watt, one joule per second, Electric power is usually produced by electric generators, but can also be supplied by sources such as electric batteries. It is usually supplied to businesses and homes by the power industry through an electric power grid. Electric power is sold by the kilowatt hour which is the product of power in kilowatts multiplied by running time in hours. Electric utilities measure power using an electricity meter, which keeps a total of the electric energy delivered to a customer. Electrical power provides a low form of energy and can be carried long distances and converted into other forms of energy such as motion. Electric power, like power, is the rate of doing work, measured in watts. The term wattage is used colloquially to mean electric power in watts, the potential energy of the charges due to the voltage between the terminals is converted to kinetic energy in the device. These devices are called passive components or loads, they consume electric power from the circuit, converting it to other forms of such as mechanical work, heat, light. Examples are electrical appliances, such as bulbs, electric motors. In alternating current circuits the direction of the voltage periodically reverses, devices in which this occurs are called active devices or power sources, such as electric generators and batteries. Some devices can be either a source or a load, depending on the voltage, for example, a rechargeable battery acts as a source when it provides power to a circuit, but as a load when it is connected to a battery charger and is being recharged. Since electric power can flow either into or out of a component, Electric power flowing out of a circuit into a component is arbitrarily defined to have a positive sign, while power flowing into a circuit from a component is defined to have a negative sign. Thus passive components have positive power consumption, while power sources have negative power consumption and this is called the passive sign convention. In alternating current circuits, energy storage such as inductance and capacitance may result in periodic reversals of the direction of energy flow. The portion of power flow that, averaged over a cycle of the AC waveform. That portion of power due to stored energy, that returns to the source in each cycle, is known as reactive power. Real power is represented as a vector and reactive power is represented as a vertical vector
6.
Electrical network
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An electrical network is an interconnection of electrical components or a model of such an interconnection, consisting of electrical elements. An electrical circuit is a network consisting of a closed loop, linear electrical networks, a special type consisting only of sources, linear lumped elements, and linear distributed elements, have the property that signals are linearly superimposable. They are thus more easily analyzed, using powerful frequency domain methods such as Laplace transforms, to determine DC response, AC response, a resistive circuit is a circuit containing only resistors and ideal current and voltage sources. Analysis of resistive circuits is less complicated than analysis of circuits containing capacitors and inductors, if the sources are constant sources, the result is a DC circuit. A network that contains active components is known as an electronic circuit. Such networks are generally nonlinear and require more complex design and analysis tools, an active network is a network that contains an active source – either a voltage source or current source. A passive network is a network that does not contain an active source, a network is linear if its signals obey the principle of superposition, otherwise it is non-linear. Sources can be classified as independent sources and dependent sources Ideal Independent Source maintains same voltage or current regardless of the elements present in the circuit. Its value is either constant or sinusoidal, the strength of voltage or current is not changed by any variation in connected network. Dependent Sources depend upon a particular element of the circuit for delivering the power or voltage or current depending upon the type of source it is, a number of electrical laws apply to all electrical networks. These include, Kirchhoffs current law, The sum of all currents entering a node is equal to the sum of all currents leaving the node, Kirchhoffs voltage law, The directed sum of the electrical potential differences around a loop must be zero. Ohms law, The voltage across a resistor is equal to the product of the resistance, nortons theorem, Any network of voltage or current sources and resistors is electrically equivalent to an ideal current source in parallel with a single resistor. Thévenins theorem, Any network of voltage or current sources and resistors is electrically equivalent to a voltage source in series with a single resistor. Other more complex laws may be needed if the network contains nonlinear or reactive components, non-linear self-regenerative heterodyning systems can be approximated. Applying these laws results in a set of equations that can be solved either algebraically or numerically. To design any electrical circuit, either analog or digital, electrical engineers need to be able to predict the voltages, simple linear circuits can be analyzed by hand using complex number theory. In more complex cases the circuit may be analyzed with specialized programs or estimation techniques such as the piecewise-linear model. More complex circuits can be analyzed numerically with software such as SPICE or GNUCAP, once the steady state solution is found, the operating points of each element in the circuit are known
7.
Steam turbine
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A steam turbine is a device that extracts thermal energy from pressurized steam and uses it to do mechanical work on a rotating output shaft. Its modern manifestation was invented by Sir Charles Parsons in 1884, in 1551, Taqi al-Din in Ottoman Egypt described a steam turbine with the practical application of rotating a spit. Steam turbines were described by the Italian Giovanni Branca and John Wilkins in England. The devices described by Taqi al-Din and Wilkins are today known as steam jacks, in 1672 an impulse steam turbine driven car was designed by Ferdinand Verbiest. A more modern version of car was produced some time in the late 18th century by an unknown German mechanic. The modern steam turbine was invented in 1884 by Sir Charles Parsons, the invention of Parsons steam turbine made cheap and plentiful electricity possible and revolutionized marine transport and naval warfare. Parsons design was a reaction type and his patent was licensed and the turbine scaled-up shortly after by an American, George Westinghouse. The Parsons turbine also turned out to be easy to scale up. Parsons had the satisfaction of seeing his invention adopted for all major world power stations, a number of other variations of turbines have been developed that work effectively with steam. The de Laval turbine accelerated the steam to full speed before running it against a turbine blade, De Lavals impulse turbine is simpler, less expensive and does not need to be pressure-proof. It can operate with any pressure of steam, but is less efficient. He taught at the École des mines de Saint-Étienne for a decade until 1897, one of the founders of the modern theory of steam and gas turbines was Aurel Stodola, a Slovak physicist and engineer and professor at the Swiss Polytechnical Institute in Zurich. His work Die Dampfturbinen und ihre Aussichten als Wärmekraftmaschinen was published in Berlin in 1903, a further book Dampf und Gas-Turbinen was published in 1922. It was used in John Brown-engined merchant ships and warships, including liners, the present-day manufacturing industry for steam turbines is dominated by Chinese power equipment makers. Other manufacturers with minor market share include Bhel, Siemens, Alstom, GE, Doosan Škoda Power, Mitsubishi Heavy Industries, the consulting firm Frost & Sullivan projects that manufacturing of steam turbines will become more consolidated by 2020 as Chinese power manufacturers win increasing business outside of China. There are several classifications for modern steam turbines, Turbine blades are of two basic types, blades and nozzles. Blades move entirely due to the impact of steam on them and this results in a steam velocity drop and essentially no pressure drop as steam moves through the blades. A turbine composed of alternating with fixed nozzles is called an impulse turbine, Curtis turbine, Rateau turbine
8.
Gas turbine
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A gas turbine, also called a combustion turbine, is a type of internal combustion engine. It has an upstream rotating compressor coupled to a turbine. The basic operation of the gas turbine is similar to that of the power plant except that the working fluid is air instead of water. Fresh atmospheric air flows through a compressor that brings it to higher pressure, energy is then added by spraying fuel into the air and igniting it so the combustion generates a high-temperature flow. This high-temperature high-pressure gas enters a turbine, where it expands down to the exhaust pressure, the turbine shaft work is used to drive the compressor and other devices such as an electric generator that may be coupled to the shaft. The energy that is not used for shaft work comes out in the exhaust gases, the purpose of the gas turbine determines the design so that the most desirable energy form is maximized. Gas turbines are used to power aircraft, trains, ships, electrical generators,50, Heros Engine — Apparently, Heros steam engine was taken to be no more than a toy, and thus its full potential not realized for centuries. 1000, The Trotting Horse Lamp was used by the Chinese at lantern fairs as early as the Northern Song dynasty. When the lamp is lit, the heated airflow rises and drives an impeller with horse-riding figures attached on it,1629, Jets of steam rotated an impulse turbine that then drove a working stamping mill by means of a bevel gear, developed by Giovanni Branca. 1678, Ferdinand Verbiest built a model carriage relying on a jet for power. 1791, A patent was given to John Barber, an Englishman and his invention had most of the elements present in the modern day gas turbines. The turbine was designed to power a horseless carriage,1861, British patent no.1633 was granted to Marc Antoine Francois Mennons for a Caloric engine. The patent shows that it was a gas turbine and the show it applied to a locomotive. Also named in the patent was Nicolas de Telescheff, a Russian aviation pioneer,1872, A gas turbine engine was designed by Franz Stolze, but the engine never ran under its own power. 1894, Sir Charles Parsons patented the idea of propelling a ship with a turbine, and built a demonstration vessel. This principle of propulsion is still of some use,1895, Three 4-ton 100 kW Parsons radial flow generators were installed in Cambridge Power Station, and used to power the first electric street lighting scheme in the city. 1899, Charles Gordon Curtis patented the first gas engine in the USA. 1900, Sanford Alexander Moss submitted a thesis on gas turbines, in 1903, Moss became an engineer for General Electrics Steam Turbine Department in Lynn, Massachusetts
9.
Water turbine
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A water turbine is a rotary machine that converts kinetic energy and potential energy of water into mechanical work. Water turbines were developed in the 19th century and were used for industrial power prior to electrical grids. Now they are used for electric power generation. Water turbines are mostly found in dams to generate power from water kinetic energy. Water wheels have been used for hundreds of years for industrial power and their main shortcoming is size, which limits the flow rate and head that can be harnessed. The migration from water wheels to modern turbines took about one hundred years, development occurred during the Industrial revolution, using scientific principles and methods. They also made use of new materials and manufacturing methods developed at the time. The word turbine was introduced by the French engineer Claude Burdin in the early 19th century and is derived from the Greek word τύρβη for whirling or a vortex. The main difference between early water turbines and water wheels is a component of the water which passes energy to a spinning rotor. This additional component of motion allowed the turbine to be smaller than a wheel of the same power. They could process more water by spinning faster and could harness much greater heads, the earliest known water turbines date to the Roman Empire. Two helix-turbine mill sites of almost identical design were found at Chemtou and Testour, modern-day Tunisia, the horizontal water wheel with angled blades was installed at the bottom of a water-filled, circular shaft. The water from the mill-race entered the pit tangentially, creating a water column which made the fully submerged wheel act like a true turbine. Fausto Veranzio in his book Machinae Novae described a vertical axis mill with a similar to that of a Francis turbine. Johann Segner developed a water turbine in the mid-18th century in Kingdom of Hungary. It had a horizontal axis and was a precursor to modern water turbines and it is a very simple machine that is still produced today for use in small hydro sites. Segner worked with Euler on some of the mathematical theories of turbine design. In the 18th century, a Dr. Barker invented a similar reaction hydraulic turbine that became popular as a lecture-hall demonstration
10.
Internal combustion engine
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An internal combustion engine is a heat engine where the combustion of a fuel occurs with an oxidizer in a combustion chamber that is an integral part of the working fluid flow circuit. In an internal combustion engine the expansion of the high-temperature and high-pressure gases produced by combustion applies direct force to some component of the engine, the force is applied typically to pistons, turbine blades, rotor or a nozzle. This force moves the component over a distance, transforming chemical energy into mechanical energy. The first commercially successful internal combustion engine was created by Étienne Lenoir around 1859, firearms are also a form of internal combustion engine. Working fluids can be air, hot water, pressurized water or even liquid sodium, ICEs are usually powered by energy-dense fuels such as gasoline or diesel, liquids derived from fossil fuels. While there are many applications, most ICEs are used in mobile applications and are the dominant power supply for vehicles such as cars, aircraft. Typically an ICE is fed with fossil fuels like natural gas or petroleum products such as gasoline, there is a growing usage of renewable fuels like biodiesel for compression ignition engines and bioethanol or methanol for spark ignition engines. Hydrogen is sometimes used, and can be made from fossil fuels or renewable energy. Various scientists and engineers contributed to the development of internal combustion engines, in 1791, John Barber developed a turbine. In 1794 Thomas Mead patented a gas engine, also in 1794 Robert Street patented an internal combustion engine, which was also the first to use liquid fuel, and built an engine around that time. In 1798, John Stevens built the first American internal combustion engine, in 1807, Swiss engineer François Isaac de Rivaz built an internal combustion engine ignited by electric spark. In 1823, Samuel Brown patented the first internal combustion engine to be applied industrially, in 1860, Belgian Jean Joseph Etienne Lenoir produced a gas-fired internal combustion engine. In 1864, Nikolaus Otto patented the first atmospheric gas engine, in 1872, American George Brayton invented the first commercial liquid-fuelled internal combustion engine. In 1876, Nikolaus Otto, working with Gottlieb Daimler and Wilhelm Maybach, patented the compressed charge, in 1879, Karl Benz patented a reliable two-stroke gas engine. In 1892, Rudolf Diesel developed the first compressed charge, compression ignition engine, in 1926, Robert Goddard launched the first liquid-fueled rocket. In 1939, the Heinkel He 178 became the worlds first jet aircraft, at one time, the word engine meant any piece of machinery — a sense that persists in expressions such as siege engine. A motor is any machine that produces mechanical power, traditionally, electric motors are not referred to as Engines, however, combustion engines are often referred to as motors. In boating an internal combustion engine that is installed in the hull is referred to as an engine, reciprocating piston engines are by far the most common power source for land and water vehicles, including automobiles, motorcycles, ships and to a lesser extent, locomotives
11.
Crank (mechanism)
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A crank is an arm attached at a right angle to a rotating shaft by which reciprocating motion is imparted to or received from the shaft. It is used to convert circular motion into reciprocating motion, or vice versa, the arm may be a bent portion of the shaft, or a separate arm or disk attached to it. Attached to the end of the crank by a pivot is a rod, the end of the rod attached to the crank moves in a circular motion, while the other end is usually constrained to move in a linear sliding motion. The term often refers to a crank which is used to manually turn an axle, as in a bicycle crankset or a brace. In this case a persons arm or leg serves as the connecting rod, there is usually a bar perpendicular to the other end of the arm, often with a freely rotatable handle or pedal attached. Familiar examples include, Mechanical pencil sharpener Fishing reel and other reels for cables, wires, ropes, manually operated car window The carpenters brace is a compound crank. The crank set that drives a handcycle through its handles, the crankset that drives a bicycle via the pedals. Treadle sewing machine Almost all reciprocating engines use cranks to transform the motion of the pistons into rotary motion. The cranks are incorporated into a crankshaft, the displacement of the end of the connecting rod is approximately proportional to the cosine of the angle of rotation of the crank, when it is measured from top dead center. The mechanical advantage of a crank, the ratio between the force on the rod and the torque on the shaft, varies throughout the cranks cycle. The relationship between the two is approximately, τ = F r sin where τ is the torque and F is the force on the connecting rod. But in reality, the torque is maximum at crank angle of less than α = 90° from TDC for a force on the piston. One way to calculate this angle is to find out when the Connecting rod smallend speed becomes the fastest in downward direction given a steady crank rotational velocity. 17615° after TDC. Then, using the sine law, it is found that the crank to connecting rod angle is 88. 21738°. When the crank is driven by the rod, a problem arises when the crank is at top dead centre or bottom dead centre. At these points in the cycle, a force on the connecting rod causes no torque on the crank. Therefore, if the crank is stationary and happens to be at one of two points, it cannot be started moving by the connecting rod. The eccentrically mounted handle of the rotary handmill which appeared in 5th century BC Celtiberian Spain, a Roman iron crank of yet unknown purpose dating to the 2nd century AD was excavated in Augusta Raurica, Switzerland
12.
Michael Faraday
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Michael Faraday FRS was an English scientist who contributed to the study of electromagnetism and electrochemistry. His main discoveries include the principles underlying electromagnetic induction, diamagnetism, although Faraday received little formal education, he was one of the most influential scientists in history. It was by his research on the field around a conductor carrying a direct current that Faraday established the basis for the concept of the electromagnetic field in physics. Faraday also established that magnetism could affect rays of light and that there was a relationship between the two phenomena. He similarly discovered the principles of induction and diamagnetism. His inventions of electromagnetic rotary devices formed the foundation of electric motor technology, Faraday ultimately became the first and foremost Fullerian Professor of Chemistry at the Royal Institution of Great Britain, a lifetime position. James Clerk Maxwell took the work of Faraday and others and summarized it in a set of equations which is accepted as the basis of all theories of electromagnetic phenomena. The SI unit of capacitance is named in his honour, the farad, albert Einstein kept a picture of Faraday on his study wall, alongside pictures of Isaac Newton and James Clerk Maxwell. Faraday was born in Newington Butts, which is now part of the London Borough of Southwark but was then a part of Surrey. His family was not well off and his father, James, was a member of the Glassite sect of Christianity. James Faraday moved his wife and two children to London during the winter of 1790 from Outhgill in Westmorland, where he had been an apprentice to the village blacksmith, Michael was born in the autumn of that year. The young Michael Faraday, who was the third of four children, at the age of 14 he became an apprentice to George Riebau, a local bookbinder and bookseller in Blandford Street. During his seven-year apprenticeship Faraday read many books, including Isaac Wattss The Improvement of the Mind, at this time he also developed an interest in science, especially in electricity. Faraday was particularly inspired by the book Conversations on Chemistry by Jane Marcet, many of the tickets for these lectures were given to Faraday by William Dance, who was one of the founders of the Royal Philharmonic Society. Faraday subsequently sent Davy a 300-page book based on notes that he had taken during these lectures, davys reply was immediate, kind, and favourable. In 1813, when Davy damaged his eyesight in an accident with nitrogen trichloride, very soon Davy entrusted Faraday with the preparation of nitrogen trichloride samples, and they both were injured in an explosion of this very sensitive substance. In the class-based English society of the time, Faraday was not considered a gentleman, Faraday was forced to fill the role of valet as well as assistant throughout the trip. Davys wife, Jane Apreece, refused to treat Faraday as an equal, the trip did, however, give him access to the scientific elite of Europe and exposed him to a host of stimulating ideas
13.
Electric power grid
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An electrical grid is an interconnected network for delivering electricity from suppliers to consumers. Power stations may be located near a source, at a dam site, or to take advantage of renewable energy sources. They are usually large to take advantage of the economies of scale. The electric power which is generated is stepped up to a voltage at which it connects to the electric power transmission network. The bulk power transmission network will move the power long distances, sometimes across international boundaries, on arrival at a substation, the power will be stepped down from a transmission level voltage to a distribution level voltage. As it exits the substation, it enters the distribution wiring, finally, upon arrival at the service location, the power is stepped down again from the distribution voltage to the required service voltage. Electrical grids vary in size covering an single building through national grids which cover whole countries. Early electric energy was produced near the device or service requiring that energy, in the 1880s, electricity competed with steam, hydraulics, and especially coal gas. Coal gas was first produced on premises but later evolved into gasification plants that enjoyed economies of scale. In the industrialized world, cities had networks of piped gas, but gas lamps produced poor light, wasted heat, made rooms hot and smoky, and gave off hydrogen and carbon monoxide. In the 1880s electric lighting soon became advantageous compared to gas lighting, Electric utility companies took advantage of economies of scale and moved to centralized power generation, distribution, and system management. With long distance power transmission it became possible to interconnect stations to balance load, merz was appointed head of a Parliamentary Committee and his findings led to the Williamson Report of 1918, which in turn created the Electricity Supply Bill of 1919. The bill was the first step towards an integrated electricity system, the Electricity Act of 1926 led to the setting up of the National Grid. The Central Electricity Board standardized the nations electricity supply and established the first synchronized AC grid and this started operating as a national system, the National Grid, in 1938. In the United States in the 1920s, utilities formed joint-operations to share peak load coverage, no longer were electric utilities built as vertical monopolies, where generation, transmission and distribution were handled by a single company. Now, the three stages could be split among various companies, in an effort to provide accessibility to high voltage transmission. The Energy Policy Act of 2005 allowed incentives and loan guarantees for energy production. In France, electrification began in the 1900s, with 700 communes in 1919, and 36,528 in 1938
14.
Electric motor
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An electric motor is an electrical machine that converts electrical energy into mechanical energy. The reverse of this is the conversion of energy into electrical energy and is done by an electric generator. In normal motoring mode, most electric motors operate through the interaction between an electric motors magnetic field and winding currents to generate force within the motor, small motors may be found in electric watches. General-purpose motors with highly standardized dimensions and characteristics provide convenient mechanical power for industrial use, the largest of electric motors are used for ship propulsion, pipeline compression and pumped-storage applications with ratings reaching 100 megawatts. Electric motors may be classified by electric power source type, internal construction, application, type of motion output, perhaps the first electric motors were simple electrostatic devices created by the Scottish monk Andrew Gordon in the 1740s. The theoretical principle behind production of force by the interactions of an electric current. The conversion of energy into mechanical energy by electromagnetic means was demonstrated by the British scientist Michael Faraday in 1821. A free-hanging wire was dipped into a pool of mercury, on which a permanent magnet was placed, when a current was passed through the wire, the wire rotated around the magnet, showing that the current gave rise to a close circular magnetic field around the wire. This motor is often demonstrated in experiments, brine substituting for toxic mercury. Though Barlows wheel was a refinement to this Faraday demonstration. In 1827, Hungarian physicist Ányos Jedlik started experimenting with electromagnetic coils, after Jedlik solved the technical problems of the continuous rotation with the invention of the commutator, he called his early devices electromagnetic self-rotors. Although they were used only for instructional purposes, in 1828 Jedlik demonstrated the first device to contain the three components of practical DC motors, the stator, rotor and commutator. The device employed no permanent magnets, as the fields of both the stationary and revolving components were produced solely by the currents flowing through their windings. His motor set a record which was improved only four years later in September 1838 by Jacobi himself. His second motor was powerful enough to drive a boat with 14 people across a wide river and it was not until 1839/40 that other developers worldwide managed to build motors of similar and later also of higher performance. The first commutator DC electric motor capable of turning machinery was invented by the British scientist William Sturgeon in 1832, following Sturgeons work, a commutator-type direct-current electric motor made with the intention of commercial use was built by the American inventor Thomas Davenport, which he patented in 1837. The motors ran at up to 600 revolutions per minute, and powered machine tools, due to the high cost of primary battery power, the motors were commercially unsuccessful and Davenport went bankrupt. Several inventors followed Sturgeon in the development of DC motors but all encountered the same battery power cost issues, no electricity distribution had been developed at the time
15.
Ganz Works
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The Ganz electric works in Budapest is probably best known for the manufacture of tramcars, but was also a pioneer in the application of three-phase alternating current to electric railways. Ganz also made ships, bridge structures and high voltage equipment. Some engineers employed by Ganz in the field were Kálmán Kandó, the company is named after Ábrahám Ganz. Before 1919, the company built ocean liners, dreadnought battleships and submarines, power plants, automobiles. The company was founded by Abraham Ganz in 1844 and he established his own iron foundry in Buda in the Kingdom of Hungary. Consequently, this played an important role in building the infrastructure of the Hungarian Kingdom. At this time the machines, steam-locomotives, pumps and the railway carriages were the main products. At the beginning of the 20th century,60 to 80% of the products were sold for export. At the end of the 19th century, the products of the Ganz and Partner Iron Mill, many engineers contributed to the Ganz Works, András Mechwart invented the hard cast rolling mill, which revolutionized the milling industry. Károly Zipernowsky participated in construction of 60 power stations, he acted as the first professor of engineering of the Budapest University of Technology. Miksa Déri developed the motor, it was used for elevators of buildings with single phase alternating current. He also participated in construction of Viennas electric supply and his whole life, Ottó Titusz Bláthy worked at the Ganz Works. His basic job was the construction and patenting of induction flow meter of 1889 used today and he invented the Turbogenerator in 1901. In the 1930s, he initiated the Hungarian production of turbogenerators, Kálmán Kandó was the first who recognised that an electric train system can only be successful if it can use the electricity from public networks. After realising that, he provided the means to build such a rail network by inventing a rotary phase converter suitable for locomotive usage. He developed high-voltage three phase alternating current motors and generators for electric locomotives, he is known as the father of the electric train, in 1878, the companys general manager András Mechwart founded the Department of Electrical Engineering headed by Károly Zipernowsky. Engineers Miksa Déri and Ottó Bláthy also worked at the department producing direct-current machines, the first turbo-generators were water turbines which propelled electric generators. The first Hungarian water turbine was designed by the engineers of the Ganz Works in 1866, the missing link of a full Voltage sensitive - voltage intensive system was the reliable AC Constant Voltage generator
16.
Zwevegem
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Zwevegem is a municipality located in the Belgian province of West Flanders. The municipality comprises the towns of Heestert, Moen, Otegem, Sint-Denijs, on January 1,2006, Zwevegem had a total population of 24,209. The total area is 63.24 km² which gives a density of 380 inhabitants per km². The Bekaert company was founded in Zwevegem by Baron Leon Leander Bekaert
17.
West Flanders
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West Flanders is the most western province of the Flemish Region, also named Flanders, in Belgium. It borders on the Netherlands, the Flemish province of East Flanders and the Walloon province of Hainaut in Belgium, on France, other important cities are Kortrijk in the south and Ostend on the coast, Roeselare and Ypres. The province has an area of 3,125 km² which is divided into eight administrative districts containing 64 municipalities, the North Sea coast of Belgium, an important tourism destination, lies in West Flanders. A tram line runs the length of the coast, from De Panne on the French border to Knokke-Heist on the Dutch border, West Flanders consists of the North Sea coast, followed by a very flat polder landscape. Only in the south are some hills, with the Kemmelberg being the highest point in the province. The Leie and IJzer are the main rivers, West Flanders is the only Belgian province that borders both France and The Netherlands. In the north of the province, most industry is concentrated in and around the cities of Bruges, both cities also have important seaports, the port of Bruges-Zeebrugge and the port of Ostend. The south is known for its industry, with companies such as Beaulieu. The region around Kortrijk is called the Dallas of Belgium for its entrepreneurship, tourism is also an important industry in West Flanders. Major touristic attractions include the Belgian coast, the center of Bruges, and Flanders Fields. The region has a distinct dialect of Dutch called West Flemish. This distinctive dialect is a part of the sense of identity of the inhabitants of the region. The city of Bruges has one playing at the highest level of football in Belgium. With Cercle Brugge it also has one playing in the Belgian First Division B. Other cities with teams playing at the highest level are Kortrijk, Ostend, the teams Knack Randstad Roeselare and Prefaxis Menen play in the highest volleyball league. Knack Randstad Roeselare also plays in the CEV Champions League, the European Championsleague, BC Oostende is a basketball team which plays in the major basketball league of Belgium. The Province of West Flanders is divided into 4 judicial arrondissements, municipalities that have city status have a behind their name. Official website of the Province of West Flanders
18.
Belgium
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Belgium, officially the Kingdom of Belgium, is a sovereign state in Western Europe bordered by France, the Netherlands, Germany, Luxembourg, and the North Sea. It is a small, densely populated country which covers an area of 30,528 square kilometres and has a population of about 11 million people. Additionally, there is a group of German-speakers who live in the East Cantons located around the High Fens area. Historically, Belgium, the Netherlands and Luxembourg were known as the Low Countries, the region was called Belgica in Latin, after the Roman province of Gallia Belgica. From the end of the Middle Ages until the 17th century, today, Belgium is a federal constitutional monarchy with a parliamentary system of governance. It is divided into three regions and three communities, that exist next to each other and its two largest regions are the Dutch-speaking region of Flanders in the north and the French-speaking southern region of Wallonia. The Brussels-Capital Region is a bilingual enclave within the Flemish Region. A German-speaking Community exists in eastern Wallonia, Belgiums linguistic diversity and related political conflicts are reflected in its political history and complex system of governance, made up of six different governments. Upon its independence, declared in 1830, Belgium participated in the Industrial Revolution and, during the course of the 20th century, possessed a number of colonies in Africa. This continuing antagonism has led to several far-reaching reforms, resulting in a transition from a unitary to a federal arrangement during the period from 1970 to 1993. Belgium is also a member of the Eurozone, NATO, OECD and WTO. Its capital, Brussels, hosts several of the EUs official seats as well as the headquarters of major international organizations such as NATO. Belgium is also a part of the Schengen Area, Belgium is a developed country, with an advanced high-income economy and is categorized as very high in the Human Development Index. A gradual immigration by Germanic Frankish tribes during the 5th century brought the area under the rule of the Merovingian kings, a gradual shift of power during the 8th century led the kingdom of the Franks to evolve into the Carolingian Empire. Many of these fiefdoms were united in the Burgundian Netherlands of the 14th and 15th centuries, the Eighty Years War divided the Low Countries into the northern United Provinces and the Southern Netherlands. The latter were ruled successively by the Spanish and the Austrian Habsburgs and this was the theatre of most Franco-Spanish and Franco-Austrian wars during the 17th and 18th centuries. The reunification of the Low Countries as the United Kingdom of the Netherlands occurred at the dissolution of the First French Empire in 1815, although the franchise was initially restricted, universal suffrage for men was introduced after the general strike of 1893 and for women in 1949. The main political parties of the 19th century were the Catholic Party, French was originally the single official language adopted by the nobility and the bourgeoisie
19.
Dynamo
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A dynamo is an electrical generator that produces direct current with the use of a commutator. Today, the simpler alternator dominates large scale power generation, for efficiency, reliability, a dynamo has the disadvantages of a mechanical commutator. Also, converting alternating to direct current using power rectification devices is effective, the word dynamo was originally another name for an electrical generator, and still has some regional usage as a replacement for the word generator. The word dynamo was coined by Werner von Siemens in 1882, the original dynamo principle of W. Siemens meant only the direct current generators which use exclusively the self-excitation principle to generate DC power. The earlier DC generators which used permanent magnets were not considered dynamo electric machines, the invention of the Dynamo principle was a huge technological leap over the old traditional permanent magnet based DC generators. The discovery of the dynamo principle made the industrial scale electric power generation technically and economically feasible, a small electrical generator built into the hub of a bicycle wheel to power lights is called a hub dynamo, although these are invariably AC devices, and are actually magnetos. The electric dynamo uses rotating coils of wire and magnetic fields to convert mechanical rotation into a direct electric current through Faradays law of induction. A dynamo machine consists of a structure, called the stator, which provides a constant magnetic field. Due to Faradays law of induction the motion of the wire within the field creates an electromotive force which pushes on the electrons in the metal. The commutator is needed to direct current. When a loop of wire rotates in a field, the magnetic flux through it. However, in the days of electric experimentation, alternating current generally had no known use. The few uses for electricity, such as electroplating, used direct current provided by messy liquid batteries, dynamos were invented as a replacement for batteries. The commutator is essentially a rotary switch and it consists of a set of contacts mounted on the machines shaft, combined with graphite-block stationary contacts, called brushes, because the earliest such fixed contacts were metal brushes. The commutator reverses the connection of the windings to the circuit when the potential reverses, so instead of alternating current. The earliest dynamos used permanent magnets to create the magnetic field and these were referred to as magneto-electric machines or magnetos. However, researchers found that magnetic fields, and so more power. These were called dynamo-electric machines or dynamos, the field coils of the stator were originally separately excited by a separate, smaller, dynamo or magneto
20.
Direct current
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Direct current is a flow of electrical charge carriers that always takes place in the same direction. The current need not always have the magnitude, but if it is to be defined as dc. This contrasts with alternating current which varies the direction of flow, sources of direct current include power supplies, electrochemical cells and batteries, and photovoltaic cells and panels. The intensity, or amplitude, of a direct current might fluctuate with time, in some such cases the dc has an ac component superimposed on it. An example of this is the output of a cell that receives a modulated light communications signal. A source of dc is sometimes called a dc generator, batteries and various other sources of dc produce a constant voltage. This is called pure dc and can be represented by a straight, the peak and effective values are the same. The peak to peak value is zero because the instantaneous amplitude never changes, in some instances the value of a dc voltage pulsates or oscillates rapidly with time, in a manner similar to the changes in an ac wave. The unfiltered output of a wave or a full wave rectifier. In 1820, Hans Christian Orsted discovered that electrical current creates a magnetic field and this discovery made scientists relate magnetism to the electric phenomena. In 1879, Thomas Edison invented the light bulb. He improved a 50-year-old idea using lower current electricity, a vacuum inside the globe and a small carbonized filament. At that time, the idea of lightning was not new. Edison not only invented an incandescent electric light, but an electric lighting system contained all the necessary elements to make the incandescent light safe, economical. Prior to 1879, direct current electricity had been used in lighting for the outdoors and it was in the 1880s when the modern electric utility industry began. It was an evolution from street lighting systems and from gas and it was located in Lower Manhattan, on Pearl Street. This station provided light and electricity to customers in a one square mile range, the station was called Thomas Edisons Pearl Street Electricity Generating Station. This station introduced four elements of an electric utility system, Efficient distribution, competitive price, reliable central generation
21.
Commutator (electric)
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It consists of a cylinder composed of multiple metal contact segments on the rotating armature of the machine. The windings on the armature are connected to the commutator segments, Commutators are used in direct current machines, dynamos and many DC motors as well as universal motors. In a motor the commutator applies electric current to the windings, by reversing the current direction in the rotating windings each half turn, a steady rotating force is produced. The first direct current commutator-type machine, the dynamo, was built by Hippolyte Pixii in 1832, Commutators are relatively inefficient, and also require periodic maintenance such as brush replacement. Therefore, commutated machines are declining in use, being replaced by alternating current machines, a commutator consists of a set of contact bars fixed to the rotating shaft of a machine, and connected to the armature windings. As the shaft rotates, the commutator reverses the flow of current in a winding, for a single armature winding, when the shaft has made one-half complete turn, the winding is now connected so that current flows through it in the opposite of the initial direction. In a motor, the current causes the fixed magnetic field to exert a rotational force, or a torque. In a generator, the torque applied to the shaft maintains the motion of the armature winding through the stationary magnetic field. Practical commutators have at least three contact segments, to prevent a dead spot where two brushes simultaneously bridge only two commutator segments, Brushes are made wider than the insulated gap, to ensure that brushes are always in contact with an armature coil. With the remaining arms, a motor can produce sufficient torque to begin spinning the rotor. Two or more fixed brushes connect to the circuit, either a source of current for a motor or a load for a generator. Commutator segments are connected to the coils of the armature, with the number of depending on the speed. Large motors may have hundreds of segments, each conducting segment of the commutator is insulated from adjacent segments. Mica was used on machines and is still used on large machines. Many other insulating materials are used to smaller machines, plastics allow quick manufacture of an insulator, for example. The segments are held onto the shaft using a shape on the edges or underside of each segment. Insulating wedges around the perimeter of each segment are pressed so that the commutator maintains its mechanical stability throughout its operating range. In small appliance and tool motors the segments are typically crimped permanently in place, when the motor fails it is discarded and replaced
22.
Alternator
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An alternator is an electrical generator that converts mechanical energy to electrical energy in the form of alternating current. For reasons of cost and simplicity, most alternators use a magnetic field with a stationary armature. Occasionally, an alternator or a rotating armature with a stationary magnetic field is used. In principle, any AC electrical generator can be called an alternator, an alternator that uses a permanent magnet for its magnetic field is called a magneto. Alternators in power stations driven by steam turbines are called turbo-alternators, large 50 or 60 Hz three phase alternators in power plants generate most of the worlds electric power, which is distributed by electric power grids. Alternating current generating systems were known in simple forms from the discovery of the induction of electric current in the 1830s. Rotating generators naturally produced alternating current but, since there was use for it, it was normally converted into direct current via the addition of a commutator in the generator. The early machines were developed by such as Michael Faraday. Faraday developed the rotating rectangle, whose operation was heteropolar – each active conductor passed successively through regions where the field was in opposite directions. Lord Kelvin and Sebastian Ferranti also developed early alternators, producing frequencies between 100 and 300 Hz, supplying the proper amount of voltage from generating stations in these early systems was left up to the engineers skill in riding the load. In 1883 the Ganz Works invented the constant voltage generator that could produce an output voltage. The introduction of transformers in the led to the widespread use of alternating current. After 1891, polyphase alternators were introduced to supply currents of multiple differing phases, later alternators were designed for various alternating current frequencies between sixteen and about one hundred hertz, for use with arc lighting, incandescent lighting and electric motors. A conductor moving relative to a magnetic field develops an electromotive force in it and this emf reverses its polarity when it moves under magnetic poles of opposite polarity. Typically, a magnet, called the rotor turns within a stationary set of conductors wound in coils on an iron core. The field cuts across the conductors, generating an induced EMF, the rotating magnetic field induces an AC voltage in the stator windings. Since the currents in the stator windings vary in step with the position of the rotor, the rotors magnetic field may be produced by permanent magnets, or by a field coil electromagnet. Automotive alternators use a rotor winding which allows control of the generated voltage by varying the current in the rotor field winding
23.
Alternating current
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Alternating current, is an electric current which periodically reverses direction, whereas direct current flows only in one direction. A common source of DC power is a cell in a flashlight. The abbreviations AC and DC are often used to mean simply alternating and direct, the usual waveform of alternating current in most electric power circuits is a sine wave. In certain applications, different waveforms are used, such as triangular or square waves, audio and radio signals carried on electrical wires are also examples of alternating current. These types of alternating current carry information encoded onto the AC signal and these currents typically alternate at higher frequencies than those used in power transmission. Electrical energy is distributed as alternating current because AC voltage may be increased or decreased with a transformer, use of a higher voltage leads to significantly more efficient transmission of power. The power losses in a conductor are a product of the square of the current and this means that when transmitting a fixed power on a given wire, if the current is halved, the power loss will be four times less. Power is often transmitted at hundreds of kilovolts, and transformed to 100–240 volts for domestic use, high voltages have disadvantages, such as the increased insulation required, and generally increased difficulty in their safe handling. In a power plant, energy is generated at a convenient voltage for the design of a generator, near the loads, the transmission voltage is stepped down to the voltages used by equipment. Consumer voltages vary somewhat depending on the country and size of load, the voltage delivered to equipment such as lighting and motor loads is standardized, with an allowable range of voltage over which equipment is expected to operate. Standard power utilization voltages and percentage tolerance vary in the different mains power systems found in the world, high-voltage direct-current electric power transmission systems have become more viable as technology has provided efficient means of changing the voltage of DC power. HVDC systems, however, tend to be expensive and less efficient over shorter distances than transformers. Three-phase electrical generation is very common, the simplest way is to use three separate coils in the generator stator, physically offset by an angle of 120° to each other. Three current waveforms are produced that are equal in magnitude and 120° out of phase to each other, if coils are added opposite to these, they generate the same phases with reverse polarity and so can be simply wired together. In practice, higher pole orders are commonly used, for example, a 12-pole machine would have 36 coils. The advantage is that lower rotational speeds can be used to generate the same frequency, for example, a 2-pole machine running at 3600 rpm and a 12-pole machine running at 600 rpm produce the same frequency, the lower speed is preferable for larger machines. If the load on a system is balanced equally among the phases. Even in the worst-case unbalanced load, the current will not exceed the highest of the phase currents
24.
Rotor (electric)
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The rotor is a moving component of an electromagnetic system in the electric motor, electric generator, or alternator. Its rotation is due to the interaction between the windings and magnetic fields which produces a torque around the rotors axis, an early example of electromagnetic rotation was the first rotary machine built by Istvan Jedlik with electromagnets and a commutator, in 1826-27. In 1835, Francis Watkins describes an electrical toy he created, induction motors, generators and alternators have an electromagnetic system consisting of a stator and rotor. There are two designs for the rotor in a motor, squirrel cage and wound. In generators and alternators, the designs are salient pole or cylindrical. The squirrel-cage rotor consists of laminated steel in the core with evenly spaced bars of copper or aluminum placed axially around the periphery and this simple and rugged construction makes it the favorite for most applications. The assembly has a twist, the bars are slanted, or skewed, to reduce magnetic hum and slot harmonics and to reduce the tendency of locking. Housed in the stator, the rotor and stator teeth can lock when they are in equal number, bearings at each end mount the rotor in its housing, with one end of the shaft protruding to allow the attachment of the load. In some motors, there is an extension at the end for speed sensors or other electronic controls. The generated torque forces motion through the rotor to the load, the rotor winding terminals are brought out and attached to the three slips rings with brushes, on the shaft of the rotor. Brushes on the rings allow for external three-phase resistors to be connected in series to the rotor windings for providing speed control. The external resistances become a part of the circuit to produce a large torque when starting the motor. As the motor speeds up, the resistances can be reduced to zero, the rotor is a large magnet with poles constructed of steel lamination projecting out of the rotor’s core. The poles are supplied by direct current or magnetized by permanent magnets, the armature with a three-phase winding is attached to three slip rings with brushes riding on them and mounted on the shaft. The field winding is wound on the rotor which produces the magnetic field, the slots are insulated from the windings and are held at the end of the rotor by slip rings. An external direct current source is connected to the concentrically mounted slip rings with brushes running along the rings, the brushes make electrical contact with the rotating slip rings. DC current is supplied through brushless excitation from a rectifier mounted on the machine shaft that converts alternating current to direct current. In a three-phase induction machine, alternating current supplied to the stator windings energizes it to create a magnetic flux
25.
Electrical machine
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In electrical engineering, electric machine is a general term for electric motors and electric generators and other electromagnetic machines. They are electromechanical energy converters, an electric motor converts electricity to power while an electric generator converts mechanical power to electricity. The moving parts in a machine can be rotating or linear, electric machines, in the form of generators, produce virtually all electric power on Earth, and in the form of electric motors consume approximately 60% of all electric power produced. Electric machines were developed beginning in the mid 19th century and since that time have been a component of the infrastructure. Developing more efficient electric machine technology is crucial to any global conservation, green energy, when classifying electric machines it is reasonable to start with physical principle for converting electric energy to mechanical energy. If the controller is included as a part of the machine all machines can be powered by alternating or direct current. Classification is complicated by the possibilities of combining physical principles when constructing an electrical machine and it can, for example, be possible to run a brushed machine as a reluctance machine if the rotor iron has the correct shape. Generally, electric machines can be turned out, so that rotor and stator exchange roles. All rotating electric machines have an equivalent linear electric machine where the moves along a straight line instead of rotating. The opposite—linear to rotary dual—is not always the case, electric machines can be synchronous meaning that the magnetic field set up by the stator coils rotates with the same speed as the rotor, or asynchronous, meaning that there is a speed difference. PM machines and reluctance machines are always synchronous, induction machines are usually asynchronous, but can be synchronous, if there are superconductors in the rotor windings. An electric generator is a device that converts energy to electrical energy. A generator forces electrons to flow through an electrical circuit. It is somewhat analogous to a pump, which creates a flow of water. The two main parts of a machine can be described in either mechanical or electrical terms. In mechanical terms, the rotor is the part. In electrical terms, the armature is the component and the field is the magnetic field component of an electrical machine. The armature can be on either the rotor or the stator, the magnetic field can be provided by either electromagnets or permanent magnets mounted on either the rotor or the stator
26.
Stator
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The stator is the stationary part of a rotary system, found in electric generators, electric motors, sirens, or biological rotors. The main use of a stator is to keep the field aligned, the first DC generators and DC motors put the field coils on the stator, and the power generation or motive reaction coils on the rotor. This is necessary because a moving power switch known as the commutator is needed to keep the field correctly aligned across the spinning rotor. The commutator must become larger and more robust as the current increases, the stator of these devices may be either a permanent magnet or an electromagnet. Where the stator is an electromagnet, the coil which energizes it is known as the coil or field winding. The coil can be either iron core or aluminum, to reduce loading losses in motors, manufacturers invariably use copper as the conducting material in windings. Aluminum, because of its electrical conductivity, may be an alternate material in fractional horsepower motors. An AC alternator is able to power across multiple high-current power generation coils connected in parallel. Placing the field coils on the rotor allows for a slip ring mechanism to transfer high-voltage. It consists of a steel frame enclosing a hollow cylindrical core, the laminations are to reduce hysteresis and eddy current losses. In a turbine, the element contains blades or ports used to redirect the flow of fluid. Such devices include the steam turbine and the torque converter, in a mechanical siren, the stator contains one or more rows of holes that admit air into the rotor, by controlling the flow of air through the holes, the sound of the siren can be altered
27.
Field coil
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A field coil is an electromagnet used to generate a magnetic field in an electro-magnetic machine, typically a rotating electrical machine such as a motor or generator. It consists of a coil of wire through which a current flows, in a rotating machine, the field coils are wound on an iron magnetic core which guides the magnetic field lines. The magnetic core is in two parts, a stator which is stationary, and a rotor, which rotates within it, the magnetic field lines pass in a continuous loop or magnetic circuit from the stator through the rotor and back through the stator again. The field coils may be on the stator or on the rotor, the magnetic path is characterized by poles, locations at equal angles around the rotor at which the magnetic field lines pass from stator to rotor or vice versa. The stator are classified by the number of poles they have, most arrangements use one field coil per pole. Some older or simpler arrangements use a field coil with a pole at each end. Although field coils are most commonly found in rotating machines, they are used, although not always with the same terminology. These include simple electromagnets through to complex lab instruments such as mass spectrometers, field coils were once widely used in loudspeakers before the general availability of lightweight permanent magnets. Most DC field coils generate a constant, static field, most three-phase AC field coils are used to generate a rotating field as part of an electric motor. Single-phase AC motors may follow either of these patterns, small motors are usually universal motors, like the brushed DC motor with a commutator, larger AC motors are generally induction motors, whether these are three- or single-phase. Many rotary electrical machines require current to be conveyed to a rotor, usually by means of sliding contacts. These contacts are often the most complex and least reliable part of such a machine and it may also represent a limit on the maximum current that the machine can handle. For this reason, when machines must use two sets of windings, the carrying the least current are usually placed on the rotor. The field coils can be mounted on either the rotor or the stator, in a brushed DC motor the field is static but the armature current must be commutated, so as to continually rotate. This is done by supplying the armature windings on the rotor through a commutator, AC induction motors also use field coils on the stator, the current on the rotor being supplied by induction in a squirrel cage. For generators, the current is smaller than the output current. Accordingly, the field is mounted on the rotor and supplied through slip rings, the output current is taken from the stator, avoiding the need for high-current sliprings. In DC generators, which are now obsolete in favour of AC generators with rectifiers
28.
Magnetic field
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A magnetic field is the magnetic effect of electric currents and magnetic materials. The magnetic field at any point is specified by both a direction and a magnitude, as such it is represented by a vector field. The term is used for two distinct but closely related fields denoted by the symbols B and H, where H is measured in units of amperes per meter in the SI, B is measured in teslas and newtons per meter per ampere in the SI. B is most commonly defined in terms of the Lorentz force it exerts on moving electric charges, Magnetic fields can be produced by moving electric charges and the intrinsic magnetic moments of elementary particles associated with a fundamental quantum property, their spin. In quantum physics, the field is quantized and electromagnetic interactions result from the exchange of photons. Magnetic fields are used throughout modern technology, particularly in electrical engineering. The Earth produces its own field, which is important in navigation. Rotating magnetic fields are used in electric motors and generators. Magnetic forces give information about the carriers in a material through the Hall effect. The interaction of magnetic fields in electric devices such as transformers is studied in the discipline of magnetic circuits, noting that the resulting field lines crossed at two points he named those points poles in analogy to Earths poles. He also clearly articulated the principle that magnets always have both a north and south pole, no matter how finely one slices them, almost three centuries later, William Gilbert of Colchester replicated Petrus Peregrinus work and was the first to state explicitly that Earth is a magnet. Published in 1600, Gilberts work, De Magnete, helped to establish magnetism as a science, in 1750, John Michell stated that magnetic poles attract and repel in accordance with an inverse square law. Charles-Augustin de Coulomb experimentally verified this in 1785 and stated explicitly that the north and south poles cannot be separated, building on this force between poles, Siméon Denis Poisson created the first successful model of the magnetic field, which he presented in 1824. In this model, a magnetic H-field is produced by magnetic poles, three discoveries challenged this foundation of magnetism, though. First, in 1819, Hans Christian Ørsted discovered that an electric current generates a magnetic field encircling it, then in 1820, André-Marie Ampère showed that parallel wires having currents in the same direction attract one another. Finally, Jean-Baptiste Biot and Félix Savart discovered the Biot–Savart law in 1820, extending these experiments, Ampère published his own successful model of magnetism in 1825. This has the benefit of explaining why magnetic charge can not be isolated. Also in this work, Ampère introduced the term electrodynamics to describe the relationship between electricity and magnetism, in 1831, Michael Faraday discovered electromagnetic induction when he found that a changing magnetic field generates an encircling electric field
29.
Magnet
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A magnet is a material or object that produces a magnetic field. This magnetic field is invisible but is responsible for the most notable property of a magnet, a force that pulls on other materials, such as iron. A permanent magnet is a made from a material that is magnetized. An everyday example is a refrigerator used to hold notes on a refrigerator door. Materials that can be magnetized, which are also the ones that are attracted to a magnet, are called ferromagnetic. These include iron, nickel, cobalt, some alloys of rare-earth metals, ferromagnetic materials can be divided into magnetically soft materials like annealed iron, which can be magnetized but do not tend to stay magnetized, and magnetically hard materials, which do. To demagnetize a saturated magnet, a magnetic field must be applied. Hard materials have high coercivity, whereas soft materials have low coercivity, an electromagnet is made from a coil of wire that acts as a magnet when an electric current passes through it but stops being a magnet when the current stops. Often, the coil is wrapped around a core of soft material such as steel. The overall strength of a magnet is measured by its magnetic moment or, alternatively, the local strength of magnetism in a material is measured by its magnetization. Ancient people learned about magnetism from lodestones, which are naturally magnetized pieces of iron ore, the word magnet in Greek meant stone from Magnesia, a part of ancient Greece where lodestones were found. Lodestones, suspended so they could turn, were the first magnetic compasses, the earliest known surviving descriptions of magnets and their properties are from Greece, India, and China around 2500 years ago. The properties of lodestones and their affinity for iron were written of by Pliny the Elder in his encyclopedia Naturalis Historia, by the 12th to 13th centuries AD, magnetic compasses were used in navigation in China, Europe, the Arabian Peninsula and elsewhere. The magnetic flux density is a vector field, the magnetic B field vector at a given point in space is specified by two properties, Its direction, which is along the orientation of a compass needle. Its magnitude, which is proportional to how strongly the compass needle orients along that direction, in SI units, the strength of the magnetic B field is given in teslas. A magnets magnetic moment is a vector that characterizes the overall magnetic properties. For a bar magnet, the direction of the moment points from the magnets south pole to its north pole. In SI units, the moment is specified in terms of A·m2
30.
Magneto
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A magneto is an electrical generator that uses permanent magnets to produce periodic pulses of alternating current. Unlike a dynamo, a magneto does not contain a commutator to produce direct current and it is categorized as a form of alternator, although it is usually regarded as distinct from most other alternators, which use field coils rather than permanent magnets. Hand-cranked magneto generators were used to provide ringing current in telephone systems, magnetos were also adapted to produce pulses of high voltage in the ignition systems of some gasoline-powered internal combustion engines to provide power to the spark plugs. Use of such ignition magnetos for ignition is now limited mainly to the kinds of engines, Engines without a low-voltage electrical system, such as lawnmowers. Aircraft engines, in keeping the ignition independent of the rest of the electrical system ensures that the engine continues running in the event of alternator or battery failure. For redundancy, virtually all piston engine aircraft are fitted with two systems, each supplying power to one of two spark plugs in each cylinder. Magnetos were used for specialized isolated power systems such as arc lamp systems or lighthouses, generators connected to an electrical grid for central station power generation do not use the magneto principle. Production of electric current from a magnetic field was demonstrated by Faraday in 1831. The first machines to produce electric current from magnetism used permanent magnets, the dynamo machine, the machine built by Hippolyte Pixii in 1832 used a rotating permanent magnet to induce alternating voltage in two fixed coils. Magnetos have advantages of simplicity and reliability, but are limited in size owing to the flux available from their permanent magnets. The fixed excitation of a made it difficult to control its terminal voltage or reactive power production when operating on a synchronized grid. This restricted their use for high-power applications, power generation magnetos were limited to narrow fields, such as powering arc lamps or lighthouses, where their particular features of output stability or simple reliability were most valued. One popular and common use of magnetos of today is for powering lights on bicycles, most commonly a small magneto, termed a bottle dynamo, rubs against the tyre of the bicycle and generates power as the wheel turns. More expensive and less common but more efficient is the hub dynamo, although commonly referred to as dynamos, both devices are in fact magnetos, producing alternating current as opposed to the direct current produced by a true dynamo. The magneto also had an application for treatment of mental illness in the beginnings of electromedicine. Magnetos adapted to produce impulses of high voltage for spark plugs are used in the systems of spark-ignition piston engines. Magnetos are used in aircraft engines for their reliability and simplicity. Motor sport vehicles such as motorcycles and snowmobiles may use magnetos because they are lighter in weight than an ignition system relying on a battery, small internal combustion engines used for lawn mowers, chain saws, portable pumps and similar applications use magnetos for economy and weight reduction
31.
Armature (electrical engineering)
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The armature, in contrast, must carry current, so it is always a conductor or a conductive coil, oriented normal to both the field and to the direction of motion, torque, or force. The first is to carry current crossing the field, thus creating shaft torque in a machine or force in a linear machine. The second role is to generate an electromotive force, in the armature, an electromotive force is created by the relative motion of the armature and the field. When the machine acts in the mode, the armature EMF drives the armature current. In an induction generator, these distinctions are blurred, since the power is drawn from the stator. A growler is used to check the armature for shorts, opens, the word armature was first used in its electrical sense, i. e. keeper of a magnet, in mid 19th century. The parts of an alternator or related equipment can be expressed in either mechanical terms or electrical terms, although distinctly separate these two sets of terminology are frequently used interchangeably or in combinations that include one mechanical term and one electrical term. This may cause confusion when working with machines like brushless alternators. In most generators, the magnet is rotating, and is part of the rotor, while the armature is stationary. Both motors and generators can be either with a stationary armature and a rotating field or a rotating armature. The pole piece of a permanent magnet or electromagnet and the moving, iron part of a solenoid, the armature can be on either the rotor or the stator. Field, The magnetic field component of an alternator, generator, dynamo or motor. The field can be on either the rotor or the stator, in a DC machine, the main field is produced by field coils. In both the generating and motoring modes, the armature carries current and a field is established. The effect of armature flux on the field is called the armature reaction. The armature reaction, demagnetizes the main field, and cross magnetizes the main field, the demagnetizing effect can be overcome by adding extra ampere-turns on the main field winding. The cross magnetizing effect can be reduced by having common poles, Armature reaction is essential in Amplidyne rotating amplifiers. Armature reaction drop is the effect of a field on the distribution of the flux under main poles of a generator. Since an armature is wound with coils of wire, a field is set up in the armature whenever a current flows in the coils
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Magnetism
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Magnetism is a class of physical phenomena that are mediated by magnetic fields. Electric currents and the moments of elementary particles give rise to a magnetic field. The most familiar effects occur in materials, which are strongly attracted by magnetic fields and can be magnetized to become permanent magnets. Only a few substances are ferromagnetic, the most common ones are iron, nickel and cobalt, the prefix ferro- refers to iron, because permanent magnetism was first observed in lodestone, a form of natural iron ore called magnetite, Fe3O4. The magnetic state of a material depends on temperature and other such as pressure. A material may exhibit more than one form of magnetism as these variables change, magnetism was first discovered in the ancient world, when people noticed that lodestones, naturally magnetized pieces of the mineral magnetite, could attract iron. The word magnet comes from the Greek term for lodestone, magnítis líthos, in ancient Greece, Aristotle attributed the first of what could be called a scientific discussion of magnetism to the philosopher Thales of Miletus, who lived from about 625 BC to about 545 BC. Around the same time, in ancient India, the Indian surgeon Sushruta was the first to use of the magnet for surgical purposes. In ancient China, the earliest literary reference to magnetism lies in a 4th-century BC book named after its author, the 2nd-century BC annals, Lüshi Chunqiu, also notes, The lodestone makes iron approach, or it attracts it. The earliest mention of the attraction of a needle is in a 1st-century work Lunheng, by the 12th century the Chinese were known to use the lodestone compass for navigation. They sculpted a directional spoon from lodestone in such a way that the handle of the spoon always pointed south, alexander Neckam, by 1187, was the first in Europe to describe the compass and its use for navigation. In 1269, Peter Peregrinus de Maricourt wrote the Epistola de magnete, in 1282, the properties of magnets and the dry compass were discussed by Al-Ashraf, a Yemeni physicist, astronomer, and geographer. In 1600, William Gilbert published his De Magnete, Magneticisque Corporibus, in this work he describes many of his experiments with his model earth called the terrella. From his experiments, he concluded that the Earth was itself magnetic and this landmark experiment is known as Ørsteds Experiment. James Clerk Maxwell synthesized and expanded these insights into Maxwells equations, unifying electricity, magnetism, in 1905, Einstein used these laws in motivating his theory of special relativity, requiring that the laws held true in all inertial reference frames. Magnetism, at its root, arises from two sources, Electric current, Spin magnetic moments of elementary particles. The magnetic moments of the nuclei of atoms are thousands of times smaller than the electrons magnetic moments. Nuclear magnetic moments are very important in other contexts, particularly in nuclear magnetic resonance
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Electricity
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Electricity is the set of physical phenomena associated with the presence of electric charge. Although initially considered a separate to magnetism, since the development of Maxwells Equations both are recognized as part of a single phenomenon, electromagnetism. Various common phenomena are related to electricity, including lightning, static electricity, electric heating, electric discharges, in addition, electricity is at the heart of many modern technologies. The presence of a charge, which can be either positive or negative. On the other hand, the movement of charges, which is known as electric current. When a charge is placed in a location with non-zero electric field, the magnitude of this force is given by Coulombs Law. Thus, if that charge were to move, the field would be doing work on the electric charge. Electrical phenomena have been studied since antiquity, though progress in theoretical understanding remained slow until the seventeenth and eighteenth centuries. Even then, practical applications for electricity were few, and it would not be until the nineteenth century that engineers were able to put it to industrial and residential use. The rapid expansion in electrical technology at this time transformed industry, electricitys 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, long before any knowledge of electricity existed, people were aware of shocks from electric fish. Ancient Egyptian texts dating from 2750 BCE referred to these fish as the Thunderer of the Nile, Electric fish were again reported millennia later by ancient Greek, Roman and Arabic naturalists and physicians. Patients suffering from such as gout or headache were directed to touch electric fish in the hope that the powerful jolt might cure them. Ancient cultures around the Mediterranean knew that certain objects, such as rods of amber, Thales was incorrect in believing the attraction was due to a magnetic effect, but later science would prove a link between magnetism and electricity. He coined the New Latin word electricus to refer to the property of attracting small objects after being rubbed and this association gave rise to the English words electric and electricity, which made their first appearance in print in Thomas Brownes Pseudodoxia Epidemica of 1646. Further work was conducted by Otto von Guericke, Robert Boyle, Stephen Gray, in the 18th century, Benjamin Franklin conducted extensive research in electricity, selling his possessions to fund his work. In June 1752 he is reputed to have attached a key to the bottom of a dampened kite string. A succession of jumping from the key to the back of his hand showed that lightning was indeed electrical in nature
34.
Electrostatics
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Electrostatics is a branch of physics that deals with the phenomena and properties of stationary or slow-moving electric charges. Since classical physics, it has known that some materials such as amber attract lightweight particles after rubbing. The Greek word for amber, ήλεκτρον, or electron, was the source of the word electricity, Electrostatic phenomena arise from the forces that electric charges exert on each other. Such forces are described by Coulombs law, Electrostatics involves the buildup of charge on the surface of objects due to contact with other surfaces. This is because the charges that transfer are trapped there for a long enough for their effects to be observed. We begin with the magnitude of the force between two point charges q and Q. It is convenient to one of these charges, q, as a test charge. As we develop the theory, more source charges will be added.854187817 ×10 −12 C2 N −1 m −2, the SI units of ε0 are equivalently A2s4 kg−1m−3 or C2N−1m−2 or F m−1. Coulombs constant is, k e ≈14 π ε0 ≈8.987551787 ×109 N m 2 C −2. A single proton has a charge of e, and the electron has a charge of −e and these physical constants are currently defined so that ε0 and k0 are exactly defined, and e is a measured quantity. Electric field lines are useful for visualizing the electric field, field lines begin on positive charge and terminate on negative charge. Electric field lines are parallel to the direction of the field. The electric field, E →, is a field that can be defined everywhere. It is convenient to place a hypothetical test charge at a point, by Coulombs Law, this test charge will experience a force that can be used to define the electric field as follow F → = q E →. For a single point charge at the origin, the magnitude of electric field is E = k e Q / R2. The fact that the force can be calculated by summing all the contributions due to individual source particles is an example of the superposition principle. If the charge is distributed over a surface or along a line, the Divergence Theorem allows Gausss Law to be written in differential form, ∇ → ⋅ E → = ρ ε0. Where ∇ → ⋅ is the divergence operator, the definition of electrostatic potential, combined with the differential form of Gausss law, provides a relationship between the potential Φ and the charge density ρ, ∇2 ϕ = − ρ ε0
35.
Electric charge
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Electric charge is the physical property of matter that causes it to experience a force when placed in an electromagnetic field. There are two types of charges, positive and negative. Like charges repel and unlike attract, an absence of net charge is referred to as neutral. An object is charged if it has an excess of electrons. The SI derived unit of charge is the coulomb. In electrical engineering, it is common to use the ampere-hour. The symbol Q often denotes charge, early knowledge of how charged substances interact is now called classical electrodynamics, and is still accurate for problems that dont require consideration of quantum effects. The electric charge is a conserved property of some subatomic particles. Electrically charged matter is influenced by, and produces, electromagnetic fields, the interaction between a moving charge and an electromagnetic field is the source of the electromagnetic force, which is one of the four fundamental forces. 602×10−19 coulombs. The proton has a charge of +e, and the electron has a charge of −e, the study of charged particles, and how their interactions are mediated by photons, is called quantum electrodynamics. Charge is the property of forms of matter that exhibit electrostatic attraction or repulsion in the presence of other matter. Electric charge is a property of many subatomic particles. The charges of free-standing particles are integer multiples of the charge e. Michael Faraday, in his electrolysis experiments, was the first to note the discrete nature of electric charge, robert Millikans oil drop experiment demonstrated this fact directly, and measured the elementary charge. By convention, the charge of an electron is −1, while that of a proton is +1, charged particles whose charges have the same sign repel one another, and particles whose charges have different signs attract. The charge of an antiparticle equals that of the corresponding particle, quarks have fractional charges of either −1/3 or +2/3, but free-standing quarks have never been observed. The electric charge of an object is the sum of the electric charges of the particles that make it up. An ion is an atom that has lost one or more electrons, giving it a net charge, or that has gained one or more electrons
36.
Electrostatic induction
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In the presence of a charged body, an insulated conductor develops a positive charge on one end and a negative charge on the other end. Induction was discovered by British scientist John Canton in 1753 and Swedish professor Johan Carl Wilcke in 1762, electrostatic generators, such as the Wimshurst machine, the Van de Graaff generator and the electrophorus, use this principle. Due to induction, the potential is constant at any point throughout a conductor. Electrostatic Induction is also responsible for the attraction of light objects, such as balloons, paper or styrofoam scraps. Electrostatic induction laws apply in situations as far as the quasistatic approximation is valid. Electrostatic induction should not be confused with Electromagnetic induction, a normal uncharged piece of matter has equal numbers of positive and negative electric charges in each part of it, located close together, so no part of it has a net electric charge. The positive charges are the atoms nuclei which are bound into the structure of matter and are not free to move, the negative charges are the atoms electrons. In electrically conductive objects such as metals, some of the electrons are able to move freely about in the object. For example, if a charge is brought near the object. When the electrons out of an area, they leave an unbalanced positive charge due to the nuclei. This results in a region of negative charge on the object nearest to the charge. If the external charge is negative, the polarity of the regions will be reversed. Since this process is just a redistribution of the charges that were already in the object, it doesnt change the charge on the object. This induction effect is reversible, if the charge is removed. However, the effect can also be used to put a net charge on an object. When the contact with ground is broken, the object is left with a net negative charge and this method can be demonstrated using a gold-leaf electroscope, which is an instrument for detecting electric charge. The electroscope is first discharged, and an object is then brought close to the instruments top terminal. Since both leaves have the charge, they repel each other and spread apart
37.
Triboelectric effect
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The triboelectric effect is a type of contact electrification in which certain materials become electrically charged after they come into frictional contact with a different material. Rubbing glass with fur, or a plastic comb through the hair, most everyday static electricity is triboelectric. The polarity and strength of the charges produced differ according to the materials, surface roughness, temperature, strain, the triboelectric effect is not very predictable, and only broad generalizations can be made. Amber, for example, can acquire a charge by contact. This property was first recorded by Thales of Miletus, the word electricity is derived from William Gilberts initial coinage, electra, which originates in the Greek word for amber, ēlektron. The prefix tribo- refers to ‘friction’, as in tribology, other examples of materials that can acquire a significant charge when rubbed together include glass rubbed with silk, and hard rubber rubbed with fur. Physical separation of materials that are adhered together results in friction between the materials, thus, a material can develop a positive or negative charge that dissipates after the materials separate. Johan Carl Wilcke published the first triboelectric series in a 1757 paper on static charges, materials are often listed in order of the polarity of charge separation when they are touched with another object. A material towards the bottom of the series, when touched to a material near the top of the series, the farther away two materials are from each other on the series, the greater the charge transferred. Materials near to other on the series may not exchange any charge. This can be caused by rubbing, by contaminants or oxides, lists vary somewhat as to the exact order of some materials, since the relative charge varies for nearby materials. From actual tests, there is little or no difference in charge affinity between metals, probably because the rapid motion of conduction electrons cancels such differences. Although the part tribo- comes from the Greek for rubbing, τρίβω, after coming into contact, a chemical bond is formed between parts of the two surfaces, called adhesion, and charges move from one material to the other to equalize their electrochemical potential. This is what creates the net imbalance between the objects. In addition, some materials may exchange ions of differing mobility, the triboelectric effect is related to friction only because they both involve adhesion. However, the effect is enhanced by rubbing the materials together, as they touch. Surface nano-effects are not well understood, and the atomic force microscope has enabled rapid progress in this field of physics, a person simply walking across a carpet may build up a potential of many thousands of volts, enough to cause a spark one centimeter long or more. Simply removing a nylon shirt or corset can also create sparks, car travel can lead to a build-up of charge on the driver and passengers due to friction between the drivers clothes and the leather or plastic furnishings inside the vehicle
38.
Voltage
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Voltage, electric potential difference, electric pressure or electric tension is the difference in electric potential energy between two points per unit electric charge. The voltage between two points is equal to the work done per unit of charge against an electric field to move the test charge between two points. This is measured in units of volts, voltage can be caused by static electric fields, by electric current through a magnetic field, by time-varying magnetic fields, or some combination of these three. A voltmeter can be used to measure the voltage between two points in a system, often a reference potential such as the ground of the system is used as one of the points. A voltage may represent either a source of energy or lost, used, given two points in space, x A and x B, voltage is the difference in electric potential between those two points. Electric potential must be distinguished from electric energy by noting that the potential is a per-unit-charge quantity. Like mechanical potential energy, the zero of electric potential can be chosen at any point, so the difference in potential, i. e. the voltage, is the quantity which is physically meaningful. The voltage between point A to point B is equal to the work which would have to be done, per unit charge, against or by the electric field to move the charge from A to B. The voltage between the two ends of a path is the energy required to move a small electric charge along that path. Mathematically this is expressed as the integral of the electric field. In the general case, both an electric field and a dynamic electromagnetic field must be included in determining the voltage between two points. Historically this quantity has also called tension and pressure. Pressure is now obsolete but tension is used, for example within the phrase high tension which is commonly used in thermionic valve based electronics. Voltage is defined so that negatively charged objects are pulled towards higher voltages, therefore, the conventional current in a wire or resistor always flows from higher voltage to lower voltage. Current can flow from lower voltage to higher voltage, but only when a source of energy is present to push it against the electric field. This is the case within any electric power source, for example, inside a battery, chemical reactions provide the energy needed for ion current to flow from the negative to the positive terminal. The electric field is not the only factor determining charge flow in a material, the electric potential of a material is not even a well defined quantity, since it varies on the subatomic scale. A more convenient definition of voltage can be found instead in the concept of Fermi level, in this case the voltage between two bodies is the thermodynamic work required to move a unit of charge between them
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Electric current
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An electric current is a flow of electric charge. In electric circuits this charge is carried by moving electrons in a wire. It can also be carried by ions in an electrolyte, or by both ions and electrons such as in an ionised gas. The SI unit for measuring a current is the ampere. Electric current is measured using a device called an ammeter, electric currents cause Joule heating, which creates light in incandescent light bulbs. They also create magnetic fields, which are used in motors, inductors and generators, the particles that carry the charge in an electric current are called charge carriers. In metals, one or more electrons from each atom are loosely bound to the atom and these conduction electrons are the charge carriers in metal conductors. The conventional symbol for current is I, which originates from the French phrase intensité de courant, current intensity is often referred to simply as current. The I symbol was used by André-Marie Ampère, after whom the unit of current is named, in formulating the eponymous Ampères force law. The notation travelled from France to Great Britain, where it became standard, in a conductive material, the moving charged particles which constitute the electric current are called charge carriers. In other materials, notably the semiconductors, the carriers can be positive or negative. Positive and negative charge carriers may even be present at the same time, a flow of positive charges gives the same electric current, and has the same effect in a circuit, as an equal flow of negative charges in the opposite direction. Since current can be the flow of positive or negative charges. The direction of current is arbitrarily defined as the same direction as positive charges flow. This is called the direction of current I. If the current flows in the direction, the variable I has a negative value. When analyzing electrical circuits, the direction of current through a specific circuit element is usually unknown. Consequently, the directions of currents are often assigned arbitrarily
40.
Insulator (electricity)
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An electrical insulator is a material whose internal electric charges do not flow freely, very little electric current will flow through it under the influence of an electric field. This contrasts with other materials, semiconductors and conductors, which conduct electric current more easily, the property that distinguishes an insulator is its resistivity, insulators have higher resistivity than semiconductors or conductors. A perfect insulator does not exist, because even insulators contain small numbers of mobile charges which can carry current, in addition, all insulators become electrically conductive when a sufficiently large voltage is applied that the electric field tears electrons away from the atoms. This is known as the voltage of an insulator. Some materials such as glass, paper and Teflon, which have high resistivity, are good electrical insulators. Examples include rubber-like polymers and most plastics which can be thermoset or thermoplastic in nature, insulators are used in electrical equipment to support and separate electrical conductors without allowing current through themselves. An insulating material used in bulk to wrap electrical cables or other equipment is called insulation, the term insulator is also used more specifically to refer to insulating supports used to attach electric power distribution or transmission lines to utility poles and transmission towers. They support the weight of the suspended wires without allowing the current to flow through the tower to ground, electrical insulation is the absence of electrical conduction. Electronic band theory says that a charge flows if states are available into which electrons can be excited and this allows electrons to gain energy and thereby move through a conductor such as a metal. If no such states are available, the material is an insulator, most insulators have a large band gap. This occurs because the valence band containing the highest energy electrons is full, there is always some voltage that gives electrons enough energy to be excited into this band. Once this voltage is exceeded the material ceases being an insulator, however, it is usually accompanied by physical or chemical changes that permanently degrade the materials insulating properties. Materials that lack electron conduction are insulators if they lack other mobile charges as well, for example, if a liquid or gas contains ions, then the ions can be made to flow as an electric current, and the material is a conductor. Electrolytes and plasmas contain ions and act as conductors whether or not electron flow is involved, when subjected to a high enough voltage, insulators suffer from the phenomenon of electrical breakdown. These freed electrons and ions are in turn accelerated and strike other atoms, creating more charge carriers, rapidly the insulator becomes filled with mobile charge carriers, and its resistance drops to a low level. In a solid, the voltage is proportional to the band gap energy. The air in a region around a conductor can break down and ionise without a catastrophic increase in current. Even a vacuum can suffer a sort of breakdown, but in case the breakdown or vacuum arc involves charges ejected from the surface of metal electrodes rather than produced by the vacuum itself
41.
X-ray tube
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An X-ray tube is a vacuum tube that converts electrical input power into X-rays. X-ray tubes evolved from experimental Crookes tubes with which X-rays were first discovered on November 8,1895, the availability of this controllable source of X-rays created the field of radiography, the imaging of partly opaque objects with penetrating radiation. In contrast to other sources of ionizing radiation, X-rays are only produced as long as the X-ray tube is energized, X-ray tubes are also used in CT scanners, airport luggage scanners, X-ray crystallography, material and structure analysis, and for industrial inspection. The anode is supported on bearings and can be rotated by electromagnetic induction from a series of stator windings outside the evacuated tube. Typically, eddy currents are induced in a metal cylinder. The superimposition of external magnetic induction and induction from the eddy currents, because the entire anode assembly has to be contained within the evacuated tube, heat removal is a serious problem, further exacerbated by the higher power rating available. Due to the heat generation, a matched thermal expansion of glass. For this, high-borate borosilicate glass pioneered by Otto Schott is often used, direct cooling by conduction or convection, as in the Coolidge tube, is difficult. In most tubes, the anode is suspended on ball bearings with silver powder lubrication which provide almost negligible cooling by conduction, a recent development has been liquid gallium lubricated fluid dynamic bearings which can withstand very high temperatures without contaminating the tube vacuum. The large bearing surface and metal lubricant provide an effective method for conduction of heat from the anode. The anode must be constructed of high temperature materials, the focal spot temperature can reach 2,500 °C during an exposure, and the anode assembly can reach 1,000 °C following a series of large exposures. Typical materials are a target on a molybdenum core, backed with graphite. The rhenium makes the tungsten more ductile and resistant to wear from the impact of the electron beams, the molybdenum conducts heat from the target. The graphite provides thermal storage for the anode, and minimizes the rotating mass of the anode, increasing demand for high-performance Computed tomography scanning and angiography systems has driven development of very high performance medical X-ray tubes. Contemporary CT tubes have power ratings of up to 100 kW and anode heat capacity of 6 MJ, some X-ray examinations need very high-resolution images and therefore require X-ray tubes that can generate very small focal spot sizes, typically below 50 µm in diameter. These tubes are called microfocus X-ray tubes, there are two basic types of microfocus X-ray tubes, solid-anode tubes and metal-jet-anode tubes. Many microfocus X-ray sources operate with focus spots in the range 5-20 µm, the major drawback of solid-anode microfocus X-ray tubes is the very low power they operate at. In order to avoid melting of the anode the electron-beam power density must be below a maximum value and this value is somewhere in the range 0. 4-0.8 W/µm depending on the anode material
42.
Particle accelerator
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A particle accelerator is a machine that uses electromagnetic fields to propel charged particles to nearly light speed and to contain them in well-defined beams. Large accelerators are used in physics as colliders, or as synchrotron light sources for the study of condensed matter physics. There are currently more than 30,000 accelerators in operation around the world, there are two basic classes of accelerators, electrostatic and electrodynamic accelerators. Electrostatic accelerators use electric fields to accelerate particles. The most common types are the Cockcroft–Walton generator and the Van de Graaff generator, a small-scale example of this class is the cathode ray tube in an ordinary old television set. The achievable kinetic energy for particles in these devices is determined by the accelerating voltage, electrodynamic or electromagnetic accelerators, on the other hand, use changing electromagnetic fields to accelerate particles. Since in these types the particles can pass through the accelerating field multiple times. This class, which was first developed in the 1920s, is the basis for most modern large-scale accelerators, because colliders can give evidence of the structure of the subatomic world, accelerators were commonly referred to as atom smashers in the 20th century. Despite the fact that most accelerators actually propel subatomic particles, the term persists in popular usage when referring to particle accelerators in general. Beams of high-energy particles are useful for both fundamental and applied research in the sciences, and also in many technical and industrial fields unrelated to fundamental research and it has been estimated that there are approximately 30,000 accelerators worldwide. The bar graph shows the breakdown of the number of industrial accelerators according to their applications, for the most basic inquiries into the dynamics and structure of matter, space, and time, physicists seek the simplest kinds of interactions at the highest possible energies. These typically entail particle energies of many GeV, and the interactions of the simplest kinds of particles, leptons and quarks for the matter, the largest and highest energy particle accelerator used for elementary particle physics is the Large Hadron Collider at CERN, operating since 2009. These investigations often involve collisions of heavy nuclei – of atoms like iron or gold – at energies of several GeV per nucleon, the largest such particle accelerator is the Relativistic Heavy Ion Collider at Brookhaven National Laboratory. An example of type of machine is LANSCE at Los Alamos. A large number of light sources exist worldwide. The ESRF in Grenoble, France has been used to extract detailed 3-dimensional images of trapped in amber. Thus there is a demand for electron accelerators of moderate energy. Everyday examples of particle accelerators are cathode ray tubes found in television sets and these low-energy accelerators use a single pair of electrodes with a DC voltage of a few thousand volts between them
43.
Faraday disk
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A homopolar generator is a DC electrical generator comprising an electrically conductive disc or cylinder rotating in a plane perpendicular to a uniform static magnetic field. A potential difference is created between the center of the disc and the rim with a polarity that depends on the direction of rotation. It is also known as a generator, acyclic generator, disk dynamo. They are unusual in that they can source tremendous electric current, some more than a million amperes, the first homopolar generator was developed by Michael Faraday during his experiments in 1831. It is frequently called the Faraday disk or Faraday wheel in his honor and it was the beginning of modern dynamos — that is, electrical generators which operate using a magnetic field. The Faraday disc was primarily inefficient due to counterflows of current, while current flow was induced directly underneath the magnet, the current would circulate backwards in regions outside the influence of the magnetic field. This counterflow limits the output to the pickup wires. Long after the original Faraday disc had been abandoned as a practical generator, sometimes the name homopolar generator is reserved for this configuration. One of the earliest patents on the type of homopolar generators was attained by A. F. Delafield. Other early patents for homopolar generators were awarded to S. Z. De Ferranti, nikola Tesla was interested in the Faraday disc and conducted work with homopolar generators, and eventually patented an improved version of the device in U. S. Teslas Dynamo Electric Machine patent describes an arrangement of two discs with separate, parallel shafts, joined like pulleys by a metallic belt. Each disc had a field that was the opposite of the other, so that the flow of current was from the one shaft to the edge, across the belt to the other disc edge. Later, patents were awarded to C. P. Steinmetz, the Forbes dynamo, developed by the Scottish electrical engineer George Forbes, was in widespread use during the beginning of the 20th century. Much of the development done in homopolar generators was patented by J. E. Noeggerath, Homopolar generators underwent a renaissance in the 1950s as a source of pulsed power storage. These devices used heavy disks as a form of flywheel to store energy that could be quickly dumped into an experimental apparatus. An early example of this sort of device was built by Sir Mark Oliphant at the Research School of Physical Sciences and Engineering and it stored up to 500 megajoules of energy and was used as an extremely high-current source for synchrotron experimentation from 1962 until it was disassembled in 1986. Oliphants construction was capable of supplying currents of up to 2 megaamperes, similar devices of even larger size are designed and built by Parker Kinetic Designs of Austin. They have produced devices for a variety of roles, from powering railguns to linear motors to a variety of weapons designs, industrial designs of 10 MJ were introduced for a variety of roles, including electrical welding
44.
Homopolar generator
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A homopolar generator is a DC electrical generator comprising an electrically conductive disc or cylinder rotating in a plane perpendicular to a uniform static magnetic field. A potential difference is created between the center of the disc and the rim with a polarity that depends on the direction of rotation. It is also known as a generator, acyclic generator, disk dynamo. They are unusual in that they can source tremendous electric current, some more than a million amperes, the first homopolar generator was developed by Michael Faraday during his experiments in 1831. It is frequently called the Faraday disk or Faraday wheel in his honor and it was the beginning of modern dynamos — that is, electrical generators which operate using a magnetic field. The Faraday disc was primarily inefficient due to counterflows of current, while current flow was induced directly underneath the magnet, the current would circulate backwards in regions outside the influence of the magnetic field. This counterflow limits the output to the pickup wires. Long after the original Faraday disc had been abandoned as a practical generator, sometimes the name homopolar generator is reserved for this configuration. One of the earliest patents on the type of homopolar generators was attained by A. F. Delafield. Other early patents for homopolar generators were awarded to S. Z. De Ferranti, nikola Tesla was interested in the Faraday disc and conducted work with homopolar generators, and eventually patented an improved version of the device in U. S. Teslas Dynamo Electric Machine patent describes an arrangement of two discs with separate, parallel shafts, joined like pulleys by a metallic belt. Each disc had a field that was the opposite of the other, so that the flow of current was from the one shaft to the edge, across the belt to the other disc edge. Later, patents were awarded to C. P. Steinmetz, the Forbes dynamo, developed by the Scottish electrical engineer George Forbes, was in widespread use during the beginning of the 20th century. Much of the development done in homopolar generators was patented by J. E. Noeggerath, Homopolar generators underwent a renaissance in the 1950s as a source of pulsed power storage. These devices used heavy disks as a form of flywheel to store energy that could be quickly dumped into an experimental apparatus. An early example of this sort of device was built by Sir Mark Oliphant at the Research School of Physical Sciences and Engineering and it stored up to 500 megajoules of energy and was used as an extremely high-current source for synchrotron experimentation from 1962 until it was disassembled in 1986. Oliphants construction was capable of supplying currents of up to 2 megaamperes, similar devices of even larger size are designed and built by Parker Kinetic Designs of Austin. They have produced devices for a variety of roles, from powering railguns to linear motors to a variety of weapons designs, industrial designs of 10 MJ were introduced for a variety of roles, including electrical welding
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Faraday's law of induction
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It is the fundamental operating principle of transformers, inductors, and many types of electrical motors, generators and solenoids. The Maxwell–Faraday equation is a generalization of Faradays law, and is listed as one of Maxwells equations, electromagnetic induction was discovered independently by Michael Faraday in 1831 and Joseph Henry in 1832. Faraday was the first to publish the results of his experiments, in Faradays first experimental demonstration of electromagnetic induction, he wrapped two wires around opposite sides of an iron ring. He plugged one wire into a galvanometer, and watched it as he connected the wire to a battery. Indeed, he saw a transient current when he connected the wire to the battery and this induction was due to the change in magnetic flux that occurred when the battery was connected and disconnected. Within two months, Faraday had found several other manifestations of electromagnetic induction, Michael Faraday explained electromagnetic induction using a concept he called lines of force. However, scientists at the time widely rejected his theoretical ideas, an exception was James Clerk Maxwell, who used Faradays ideas as the basis of his quantitative electromagnetic theory. Heavisides version is the form recognized today in the group of known as Maxwells equations. Lenzs law, formulated by Heinrich Lenz in 1834, describes flux through the circuit, a different version, the Maxwell–Faraday equation, is valid in all circumstances. Faradays law of induction makes use of the magnetic flux ΦB through a hypothetical surface Σ whose boundary is a wire loop, since the wire loop may be moving, we write Σ for the surface. In more visual terms, the flux through the wire loop is proportional to the number of magnetic flux lines that pass through the loop. Equivalently, it is the voltage that would be measured by cutting the wire to create an open circuit, and attaching a voltmeter to the leads. Faradays law states that the EMF is also given by the rate of change of the flux, E = − d Φ B d t. The direction of the force is given by Lenzs law. The Maxwell–Faraday equation is where ∇ × is the operator and again E is the electric field. These fields can generally be functions of position r and time t, the Maxwell–Faraday equation is one of the four Maxwells equations, and therefore plays a fundamental role in the theory of classical electromagnetism. Dl is an infinitesimal element of the contour ∂Σ, dA is an infinitesimal vector element of surface Σ. If its direction is orthogonal to that surface patch, the magnitude is the area of a patch of surface
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Electromotive force
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Electromotive force, also called emf, is the voltage developed by any source of electrical energy such as a battery or dynamo. It is generally defined as the potential for a source in a circuit. A device that supplies electrical energy is called electromotive force or emf, emfs convert chemical, mechanical, and other forms of energy into electrical energy. The product of such a device is known as emf. The word force in case is not used to mean mechanical force, measured in newtons. In electromagnetic induction, emf can be defined around a loop as the electromagnetic work that would be done on a charge if it travels once around that loop. This potential difference can drive a current if a circuit is attached to the terminals. Devices that can provide emf include electrochemical cells, thermoelectric devices, solar cells, photodiodes, electrical generators, transformer, in nature, emf is generated whenever magnetic field fluctuations occur through a surface. The shifting of the Earths magnetic field during a geomagnetic storm, … By chemical, mechanical or other means, the source of emf performs work dW on that charge to move it to the high potential terminal. The emf ℰ of the source is defined as the work dW done per charge dq, in the open-circuit case, charge separation continues until the electrical field from the separated charges is sufficient to arrest the reactions. Again the emf is countered by the voltage due to charge separation. If a load is attached, this voltage can drive a current, the general principle governing the emf in such electrical machines is Faradays law of induction. Electromotive force is often denoted by E or ℰ, in a device without internal resistance, if an electric charge Q passes through that device, and gains an energy W, the net emf for that device is the energy gained per unit charge, or J/Q. Like other measures of energy per charge, emf has SI units of volts, Electromotive force in electrostatic units is the statvolt. Inside a source of emf that is open-circuited, the electrostatic field created by separation of charge exactly cancels the forces producing the emf. Thus, the emf has the same value but opposite sign as the integral of the field aligned with an internal path between two terminals A and B of a source of emf in open-circuit condition. This equation applies only to locations A and B that are terminals and this equation involves the electrostatic electric field due to charge separation Ecs and does not involve any non-conservative component of electric field due to Faradays law of induction. The electrostatic field does not contribute to the net emf around a circuit because the portion of the electric field is conservative
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Magnetic flux
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In physics, specifically electromagnetism, the magnetic flux through a surface is the surface integral of the normal component of the magnetic field B passing through that surface. The SI unit of flux is the weber, and the CGS unit is the maxwell. Magnetic flux is measured with a fluxmeter, which contains measuring coils and electronics. The magnetic interaction is described in terms of a vector field, since a vector field is quite difficult to visualize at first, in elementary physics one may instead visualize this field with field lines. The magnetic flux through some surface, in this picture, is proportional to the number of field lines passing through that surface. In more advanced physics, the field line analogy is dropped, for a varying magnetic field, we first consider the magnetic flux through an infinitesimal area element dS, where we may consider the field to be constant, d Φ B = B ⋅ d S. This law is a consequence of the observation that magnetic monopoles have never been found. In other words, Gausss law for magnetism is the statement, while the magnetic flux through a closed surface is always zero, the magnetic flux through an open surface need not be zero and is an important quantity in electromagnetism. For example, a change in the flux passing through a loop of conductive wire will cause an electromotive force. The electromotive force is induced along this boundary, dℓ is an infinitesimal vector element of the contour ∂Σ, v is the velocity of the boundary ∂Σ, E is the electric field, B is the magnetic field. This equation is the principle behind an electrical generator, note that the flux of E through a closed surface is not always zero, this indicates the presence of electric monopoles, that is, free positive or negative charges. Gausss law gives the relation between the electric flux flowing out a surface and the electric charge enclosed in the surface. Magnetic circuit is a method using an analogy with electric circuits to calculate the flux of complex systems of magnetic components, Magnetic monopole is a hypothetical particle that may loosely be described as a magnet with only 1 pole. Magnetic flux quantum is the quantum of magnetic flux passing through a superconductor, carl Friedrich Gauss developed a fruitful collaboration with the physics professor Wilhelm Weber, it led to new knowledge in the field of magnetism. James Clerk Maxwell demonstrated that electric and magnetic forces are two aspects of electromagnetism. Patent 6,720,855, Magnetic-flux conduits Magnetic Flux through a Loop of Wire by Ernest Lee, conversion Magnetic flux Φ in nWb per meter track width to flux level in dB - Tape Operating Levels and Tape Alignment Levels
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Copper
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Copper is a chemical element with symbol Cu and atomic number 29. It is a soft, malleable, and ductile metal with high thermal and electrical conductivity. A freshly exposed surface of copper has a reddish-orange color. Copper is one of the few metals that occur in nature in directly usable metallic form as opposed to needing extraction from an ore and this led to very early human use, from c.8000 BC. Copper used in buildings, usually for roofing, oxidizes to form a green verdigris, Copper is sometimes used in decorative art, both in its elemental metal form and in compounds as pigments. Copper compounds are used as agents, fungicides, and wood preservatives. Copper is essential to all living organisms as a trace dietary mineral because it is a key constituent of the enzyme complex cytochrome c oxidase. In molluscs and crustaceans, copper is a constituent of the blood pigment hemocyanin, replaced by the hemoglobin in fish. In humans, copper is found mainly in the liver, muscle, the adult body contains between 1.4 and 2.1 mg of copper per kilogram of body weight. The filled d-shells in these elements contribute little to interatomic interactions, unlike metals with incomplete d-shells, metallic bonds in copper are lacking a covalent character and are relatively weak. This observation explains the low hardness and high ductility of single crystals of copper, at the macroscopic scale, introduction of extended defects to the crystal lattice, such as grain boundaries, hinders flow of the material under applied stress, thereby increasing its hardness. For this reason, copper is supplied in a fine-grained polycrystalline form. The softness of copper partly explains its high conductivity and high thermal conductivity. The maximum permissible current density of copper in open air is approximately 3. 1×106 A/m2 of cross-sectional area, Copper is one of a few metallic elements with a natural color other than gray or silver. Pure copper is orange-red and acquires a reddish tarnish when exposed to air, as with other metals, if copper is put in contact with another metal, galvanic corrosion will occur. A green layer of verdigris can often be seen on old structures, such as the roofing of many older buildings. Copper tarnishes when exposed to sulfur compounds, with which it reacts to form various copper sulfides. There are 29 isotopes of copper, 63Cu and 65Cu are stable, with 63Cu comprising approximately 69% of naturally occurring copper, both have a spin of 3⁄2
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