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Electrical engineering is an engineering discipline concerned with the study, design, and application of equipment, devices, and systems which use electricity, electronics, and electromagnetism. It emerged as an identifiable occupation in the latter half of the 19th century after the commercialization of the electric telegraph, the telephone, and electrical power generation, distribution, and use.
In physics, electromagnetism is an interaction that occurs between particles with electric charge via electromagnetic fields. The electromagnetic force is one of the four fundamental forces of nature. It is the dominant force in the interactions of atoms and molecules. Electromagnetism can be thought of as a combination of electrostatics and magnetism, which are distinct but closely intertwined phenomena. Electromagnetic forces occur between any two charged particles. Electric forces cause an attraction between particles with opposite charges and repulsion between particles with the same charge, while magnetism is an interaction that occurs between charged particles in relative motion. These two forces are described in terms of electromagnetic fields. Macroscopic charged objects are described in terms of Coulomb's law for electricity and Ampère's force law for magnetism; the Lorentz force describes microscopic charged particles.
In electrical engineering, a transformer is a passive component that transfers electrical energy from one electrical circuit to another circuit, or multiple circuits. A varying current in any coil of the transformer produces a varying magnetic flux in the transformer's core, which induces a varying electromotive force (EMF) across any other coils wound around the same core. Electrical energy can be transferred between separate coils without a metallic (conductive) connection between the two circuits. Faraday's law of induction, discovered in 1831, describes the induced voltage effect in any coil due to a changing magnetic flux encircled by the coil.
An electromagnet is a type of magnet in which the magnetic field is produced by an electric current. Electromagnets usually consist of wire wound into a coil. A current through the wire creates a magnetic field which is concentrated in the hole in the center of the coil. The magnetic field disappears when the current is turned off. The wire turns are often wound around a magnetic core made from a ferromagnetic or ferrimagnetic material such as iron; the magnetic core concentrates the magnetic flux and makes a more powerful magnet.
Hysteresis is the dependence of the state of a system on its history. For example, a magnet may have more than one possible magnetic moment in a given magnetic field, depending on how the field changed in the past. Plots of a single component of the moment often form a loop or hysteresis curve, where there are different values of one variable depending on the direction of change of another variable. This history dependence is the basis of memory in a hard disk drive and the remanence that retains a record of the Earth's magnetic field magnitude in the past. Hysteresis occurs in ferromagnetic and ferroelectric materials, as well as in the deformation of rubber bands and shape-memory alloys and many other natural phenomena. In natural systems, it is often associated with irreversible thermodynamic change such as phase transitions and with internal friction; and dissipation is a common side effect.
Remanence or remanent magnetization or residual magnetism is the magnetization left behind in a ferromagnetic material after an external magnetic field is removed. Colloquially, when a magnet is "magnetized", it has remanence. The remanence of magnetic materials provides the magnetic memory in magnetic storage devices, and is used as a source of information on the past Earth's magnetic field in paleomagnetism. The word remanence is from remanent + -ence, meaning "that which remains".
Coercivity, also called the magnetic coercivity, coercive field or coercive force, is a measure of the ability of a ferromagnetic material to withstand an external magnetic field without becoming demagnetized. Coercivity is usually measured in oersted or ampere/meter units and is denoted HC.
The following outline is provided as an overview of and topical guide to electrical engineering.
In classical electromagnetism, magnetization is the vector field that expresses the density of permanent or induced magnetic dipole moments in a magnetic material. Accordingly, physicists and engineers usually define magnetization as the quantity of magnetic moment per unit volume. It is represented by a pseudovector M. Magnetization can be compared to electric polarization, which is the measure of the corresponding response of a material to an electric field in electrostatics.
This is an alphabetical list of articles pertaining specifically to electrical and electronics engineering. For a thematic list, please see List of electrical engineering topics. For a broad overview of engineering, see List of engineering topics. For biographies, see List of engineers.
Oleg V. Tozoni was a scientist, inventor, and a specialist in the field of electro-dynamic and electrical engineering. Since 1964 through 1988 Tozoni was the Head of the Department of Electrodynamics at the Cybernetics Institute of the Academy of Science, USSR. After immigration to the U.S. in 1989, Tozoni worked as a Visiting Research Professor at the University of Maryland, Department of Electrical Engineering. He resided in Maryland and continued to work developing his MDS maglev system until his death. His work continues to be developed by TozoniMAGLEV, L.L.C.
In electromagnetism, the Preisach model of hysteresis is a model of magnetic hysteresis. Originally, it generalized hysteresis as the relationship between the magnetic field and magnetization of a magnetic material as the parallel connection of independent relay hysterons. It was first suggested in 1935 by Ferenc (Franz) Preisach in the German academic journal Zeitschrift für Physik. In the field of ferromagnetism, the Preisach model is sometimes thought to describe a ferromagnetic material as a network of small independently acting domains, each magnetized to a value of either or . A sample of iron, for example, may have evenly distributed magnetic domains, resulting in a net magnetic moment of zero.
A nonlinear dynamical system exhibits chaotic hysteresis if it simultaneously exhibits chaotic dynamics and hysteresis. As the latter involves the persistence of a state, such as magnetization, after the causal or exogenous force or factor is removed, it involves multiple equilibria for given sets of control conditions. Such systems generally exhibit sudden jumps from one equilibrium state to another. If chaotic dynamics appear either prior to or just after such jumps, or are persistent throughout each of the various equilibrium states, then the system is said to exhibit chaotic hysteresis. Chaotic dynamics are irregular and bounded and subject to sensitive dependence on initial conditions.
Vladimir (Vlad) M. Shalaev is a Distinguished Professor of Electrical and Computer Engineering and Scientific Director for Nanophotonics at Birck Nanotechnology Center, Purdue University.
A nanolaser is a laser that has nanoscale dimensions and it refers to a micro-/nano- device which can emit light with light or electric excitation of nanowires or other nanomaterials that serve as resonators. A standard feature of nanolasers includes their light confinement on a scale approaching or suppressing the diffraction limit of light. These tiny lasers can be modulated quickly and, combined with their small footprint, this makes them ideal candidates for on-chip optical computing.
Kang Lung Wang is recognized as the discoverer of chiral Majorana fermions by IUPAP. Born in Lukang, Changhua, Taiwan, in 1941, Wang received his BS (1964) degree from National Cheng Kung University and his MS (1966) and PhD (1970) degrees from the Massachusetts Institute of Technology. In 1970 to 1972 he was the Assistant Professor at MIT. From 1972 to 1979, he worked at the General Electric Corporate Research and Development Center as a physicist/engineer. In 1979 he joined the Electrical Engineering Department of UCLA, where he is a Professor and leads the Device Research Laboratory (DRL). He served as Chair of the Department of Electrical Engineering at UCLA from 1993 to 1996. His research activities include semiconductor nano devices, and nanotechnology; self-assembly growth of quantum structures and cooperative assembly of quantum dot arrays Si-based Molecular Beam Epitaxy, quantum structures and devices; Nano-epitaxy of hetero-structures; Spintronics materials and devices; Electron spin and coherence properties of SiGe and InAs quantum structures for implementation of spin-based quantum information; microwave devices. He was the inventor of strained layer MOSFET, quantum SRAM cell, and band-aligned superlattices. He holds 45 patents and published over 700 papers. He is a passionate teacher and has mentored hundreds of students, including MS and PhD candidates. Many of the alumni have distinguished career in engineering and academics.
Plasmonics or nanoplasmonics refers to the generation, detection, and manipulation of signals at optical frequencies along metal-dielectric interfaces in the nanometer scale. Inspired by photonics, plasmonics follows the trend of miniaturizing optical devices, and finds applications in sensing, microscopy, optical communications, and bio-photonics.
Govind P. Agrawal is an Indian American physicist and a fellow of Optica, Life Fellow of the IEEE, and Distinguished Fellow of the Optical Society of India. He is the recipient of James C. Wyant Professorship of Optics at the Institute of Optics and a professor of physics at the University of Rochester. He is also a Distinguished scientist at the Laboratory for Laser Energetics (LLE) in the University of Rochester. Agrawal has authored and co-authored several highly cited books in the fields of non-linear fiber optics, optical communications, and semiconductor lasers.
Roger Fuller Harrington is an American electrical engineer and professor emeritus at Syracuse University. He is best known for his contributions to computational electromagnetics with his development of method of moments (MoM). Harrington's 1968 book, Field Computation by Moment Methods, is regarded as a pivotal textbook on the subject.
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