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Electrical engineering is an engineering discipline concerned with the study, design, and application of equipment, devices, and systems that 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.
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.
Seen in some magnetic materials, saturation is the state reached when an increase in applied external magnetic field H cannot increase the magnetization of the material further, so the total magnetic flux density B more or less levels off. Saturation is a characteristic of ferromagnetic and ferrimagnetic materials, such as iron, nickel, cobalt and their alloys. Different ferromagnetic materials have different saturation levels.
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.
This article details the history of electrical engineering.
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.
A plasmonic-enhanced solar cell, commonly referred to simply as plasmonic solar cell, is a type of solar cell that converts light into electricity with the assistance of plasmons, but where the photovoltaic effect occurs in another material.
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.
Prashant Jain is an Indian-born American scientist and a professor of chemistry at the University of Illinois Urbana–Champaign where his research laboratory studies the interaction of light with matter, designs nanoparticle catalysts, and develops methods for mimicking plant photosynthesis. He is a Fellow of the American Association for the Advancement of Science and the Royal Society of Chemistry, a TR35 inventor, a Sloan Fellow, a PECASE recipient, a Royal Society of Chemistry Beilby medalist, and a top-cited researcher in chemical sciences.
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