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Electromagnetic Induction Electromagnetic or magnetic induction is the production of an electromotive force (i.e., voltage) across an electrical conductor in a changing magnetic field. Michael Faraday Michael Faraday is generally credited with the discovery of induction in 1831, and James Clerk Maxwell James Clerk Maxwell mathematically described it as Faraday's law of induction. Lenz's law Lenz's law describes the direction of the induced field [...More...]  "Electromagnetic Induction" on: Wikipedia Yahoo 

Electrical Network An electrical network is an interconnection of electrical components (e.g. batteries, resistors, inductors, capacitors, switches) or a model of such an interconnection, consisting of electrical elements (e.g. voltage sources, current sources, resistances, inductances, capacitances). An electrical circuit is a network consisting of a closed loop, giving a return path for the current. Linear electrical networks, a special type consisting only of sources (voltage or current), linear lumped elements (resistors, capacitors, inductors), and linear distributed elements (transmission lines), 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, and transient response. A resistive circuit is a circuit containing only resistors and ideal current and voltage sources [...More...]  "Electrical Network" on: Wikipedia Yahoo 

Eddy Current Eddy currents Eddy currents (also called Foucault currents) are loops of electrical current induced within conductors by a changing magnetic field in the conductor due to Faraday's law of induction. Eddy currents Eddy currents flow in closed loops within conductors, in planes perpendicular to the magnetic field. They can be induced within nearby stationary conductors by a timevarying magnetic field created by an AC electromagnet or transformer, for example, or by relative motion between a magnet and a nearby conductor. The magnitude of the current in a given loop is proportional to the strength of the magnetic field, the area of the loop, and the rate of change of flux, and inversely proportional to the resistivity of the material. By Lenz's law, an eddy current creates a magnetic field that opposes the change in the magnetic field that created it, and thus eddy currents react back on the source of the magnetic field [...More...]  "Eddy Current" on: Wikipedia Yahoo 

Electromagnetic Pulse An electromagnetic pulse (EMP), also sometimes called a transient electromagnetic disturbance, is a short burst of electromagnetic energy. Such a pulse's origination may be a natural occurrence or manmade and can occur as a radiated, electric, or magnetic field or a conducted electric current, depending on the source. EMP interference is generally disruptive or damaging to electronic equipment, and at higher energy levels a powerful EMP event such as a lightning strike can damage physical objects such as buildings and aircraft structures [...More...]  "Electromagnetic Pulse" on: Wikipedia Yahoo 

James Clerk Maxwell James Clerk Maxwell James Clerk Maxwell FRS FRSE (/ˈmækswɛl/;[2] 13 June 1831 – 5 November 1879) was a Scottish[3][4] scientist in the field of mathematical physics.[5] His most notable achievement was to formulate the classical theory of electromagnetic radiation, bringing together for the first time electricity, magnetism, and light as different manifestations of the same phenomenon. Maxwell's equations Maxwell's equations for electromagnetism have been called the "second great unification in physics"[6] after the first one realised by Isaac Newton. With the publication of "A Dynamical Theory of the Electromagnetic Field" in 1865, Maxwell demonstrated that electric and magnetic fields travel through space as waves moving at the speed of light [...More...]  "James Clerk Maxwell" on: Wikipedia Yahoo 

Electric Generator In electricity generation, a generator[1] is a device that converts motive power (mechanical energy) into electrical power for use in an external circuit. Sources of mechanical energy include steam turbines, gas turbines, water turbines, internal combustion engines and even hand cranks. The first electromagnetic generator, the Faraday disk, was built in 1831 by British scientist Michael Faraday. Generators provide nearly all of the power for electric power grids. The reverse conversion of electrical energy into mechanical energy is done by an electric motor, and motors and generators have many similarities [...More...]  "Electric Generator" on: Wikipedia Yahoo 

Gauss's Law For Magnetism In physics, Gauss's law Gauss's law for magnetism is one of the four Maxwell's equations that underlie classical electrodynamics. It states that the magnetic field B has divergence equal to zero,[1] in other words, that it is a solenoidal vector field. It is equivalent to the statement that magnetic monopoles do not exist.[2] Rather than "magnetic charges", the basic entity for magnetism is the magnetic dipole. (If monopoles were ever found, the law would have to be modified, as elaborated below.) Gauss's law Gauss's law for magnetism can be written in two forms, a differential form and an integral form. These forms are equivalent due to the divergence theorem. The name " Gauss's law Gauss's law for magnetism"[1] is not universally used [...More...]  "Gauss's Law For Magnetism" on: Wikipedia Yahoo 

Polarization Density In classical electromagnetism, polarization density (or electric polarization, or simply polarization) is the vector field that expresses the density of permanent or induced electric dipole moments in a dielectric material. When a dielectric is placed in an external electric field, its molecules gain electric dipole moment and the dielectric is said to be polarized. The electric dipole moment induced per unit volume of the dielectric material is called the electric polarization of the dielectric.[1][2] Polarization density Polarization density also describes how a material responds to an applied electric field as well as the way the material changes the electric field, and can be used to calculate the forces that result from those interactions. It can be compared to magnetization, which is the measure of the corresponding response of a material to a magnetic field in magnetism [...More...]  "Polarization Density" on: Wikipedia Yahoo 

Magnetostatics Magnetostatics Magnetostatics is the study of magnetic fields in systems where the currents are steady (not changing with time). It is the magnetic analogue of electrostatics, where the charges are stationary. The magnetization need not be static; the equations of magnetostatics can be used to predict fast magnetic switching events that occur on time scales of nanoseconds or less.[1] Magnetostatics Magnetostatics is even a good approximation when the currents are not static — as long as the currents do not alternate rapidly. Magnetostatics Magnetostatics is widely used in applications of micromagnetics such as models of magnetic recording devices [...More...]  "Magnetostatics" on: Wikipedia Yahoo 

Ampère's Circuital Law In classical electromagnetism, Ampère's circuital law Ampère's circuital law (not to be confused with Ampère's force law Ampère's force law that AndréMarie Ampère AndréMarie Ampère discovered in 1823[1]) relates the integrated magnetic field around a closed loop to the electric current passing through the loop [...More...]  "Ampère's Circuital Law" on: Wikipedia Yahoo 

Magnetization In classical electromagnetism, magnetization or magnetic polarization is the vector field that expresses the density of permanent or induced magnetic dipole moments in a magnetic material. The origin of the magnetic moments responsible for magnetization can be either microscopic electric currents resulting from the motion of electrons in atoms, or the spin of the electrons or the nuclei. Net magnetization results from the response of a material to an external magnetic field, together with any unbalanced magnetic dipole moments that may be inherent in the material itself; for example, in ferromagnets. Magnetization Magnetization is not always uniform within a body, but rather varies between different points. Magnetization Magnetization also describes how a material responds to an applied magnetic field as well as the way the material changes the magnetic field, and can be used to calculate the forces that result from those interactions [...More...]  "Magnetization" on: Wikipedia Yahoo 

Magnetic Flux In physics, specifically electromagnetism, the magnetic flux (often denoted Φ or ΦB) through a surface is the surface integral of the normal component of the magnetic field B passing through that surface. The SI unit of magnetic flux is the weber (Wb) (in derived units: voltseconds), and the CGS unit is the maxwell [...More...]  "Magnetic Flux" on: Wikipedia Yahoo 

Biot–Savart Law In physics, specifically electromagnetism, the Biot–Savart law (/ˈbiːoʊ səˈvɑːr/ or /ˈbjoʊ səˈvɑːr/)[1] is an equation describing the magnetic field generated by a stationary electric current. It relates the magnetic field to the magnitude, direction, length, and proximity of the electric current. The Biot–Savart law is fundamental to magnetostatics, playing a similar role to Coulomb's law in electrostatics. When magnetostatics does not apply, the Biot–Savart law Biot–Savart law should be replaced by Jefimenko's equations [...More...]  "Biot–Savart Law" on: Wikipedia Yahoo 

Magnetic Moment The magnetic moment of a magnet is a quantity that determines the torque it will experience in an external magnetic field. A loop of electric current, a bar magnet, an electron, a molecule, and a planet all have magnetic moments. The magnetic moment may be considered to be a vector having a magnitude and direction. The direction of the magnetic moment points from the south to north pole of the magnet (inside the magnet). The magnetic field produced by the magnet is proportional to its magnetic moment. More precisely, the term magnetic moment normally refers to a system's magnetic dipole moment, which produces the first term in the multipole expansion of a general magnetic field [...More...]  "Magnetic Moment" on: Wikipedia Yahoo 

Magnetic Potential The term magnetic potential can be used for either of two quantities in classical electromagnetism: the magnetic vector potential, A, (often simply called the vector potential) and the magnetic scalar potential, ψ. Both quantities can be used in certain circumstances to calculate the magnetic field. The more frequently used magnetic vector potential, A, is defined such that the curl of A is the magnetic field B. Together with the electric potential, the magnetic vector potential can be used to specify the electric field, E as well. Therefore, many equations of electromagnetism can be written either in terms of the E and B, or in terms of the magnetic vector potential and electric potential [...More...]  "Magnetic Potential" on: Wikipedia Yahoo 

Classical Electromagnetism Classical electromagnetism Classical electromagnetism or classical electrodynamics is a branch of theoretical physics that studies the interactions between electric charges and currents using an extension of the classical Newtonian model. The theory provides an excellent description of electromagnetic phenomena whenever the relevant length scales and field strengths are large enough that quantum mechanical effects are negligible [...More...]  "Classical Electromagnetism" on: Wikipedia Yahoo 