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Electromagnetic induction

Electromagnetic induction
Electromagnetic induction is the production of a potential difference (voltage) across a conductor when it is exposed to a varying magnetic field. It is described mathematically by Faraday's law of induction, named after Michael Faraday who is generally credited with the discovery of induction in 1831. History[edit] A diagram of Faraday's iron ring apparatus. Change in the magnetic flux of the left coil induces a current in the right coil.[1] Electromagnetic induction was discovered independently by Michael Faraday and Joseph Henry in 1831; however, Faraday was the first to publish the results of his experiments.[2][3] In Faraday's first experimental demonstration of electromagnetic induction (August 29, 1831[4]), he wrapped two wires around opposite sides of an iron ring or "torus" (an arrangement similar to a modern toroidal transformer). Faraday explained electromagnetic induction using a concept he called lines of force. Faraday's law and the Maxwell–Faraday equation[edit] where

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Alternator In principle, any AC electrical generator can be called an alternator, but usually the term refers to small rotating machines driven by automotive and other internal combustion engines. 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.

Synchronous motor A synchronous motor-generator set for AC to DC conversion. Small synchronous motor and integral stepdown gear from a microwave oven Synchronous motors are available in sub-fractional self-excited sizes[2] to high-horsepower industrial sizes.[1] In the fractional horsepower range, most synchronous motors are used where precise constant speed is required. In high-horsepower industrial sizes, the synchronous motor provides two important functions. First, it is a highly efficient means of converting AC energy to work. Second, it can operate at leading or unity power factor and thereby provide power-factor correction. Transcranial magnetic stimulation Background[edit] Early attempts at stimulation of the brain using a magnetic field included those, in 1910, of Silvanus P. Thompson in London.[2] The principle of inductive brain stimulation with eddy currents has been noted since the 20th century.

Radial Air core alternator Radial Air core alternator Fun! These are simple radial air core alternators that anyone with a drill and jig saw can build. Below are the basic parts for a single magnet 3 phase alternator... Induction generator An induction generator or asynchronous generator is a type of AC electrical generator that uses the principles of induction motors to produce power. Induction generators operate by mechanically turning their rotor faster than the synchronous speed. A regular AC asynchronous motor usually can be used as a generator, without any internal modifications. Induction generators are useful in applications such as mini hydro power plants, wind turbines, or in reducing high-pressure gas streams to lower pressure, because they can recover energy with relatively simple controls. An induction generator must be excited with a leading voltage.

US runs warzone man-tracking 'Manhattan Project' A long-running background mutter has now become a loud buzz of speculation, following cryptic comments by a famous US journalist regarding a top secret new surveillance-tech "Manhattan Project" targeting terrorist and insurgent leaders in Iraq. Bob Woodward of the Washington Post - famous for his reporting of leaks by a senior FBI official regarding the Watergate scandals of the 1970s - makes the claims in a new book, which he is currently engaged in trailing. He says that the current reduction in violence being seen in Iraq is partly, as everyone assumes, a result of visible factors - the Sunni "awakening" against al-Qaeda in Iraq, the ceasefire by important Shi'ite militias, and the US troop "surge" in which many more American soldiers have been operating on the ground outside their secure bases. "It is a wonderful example of American ingenuity solving a problem in war, as we often have," said Woodward in a recent TV interview.

Transformer A transformer is an electrical device that transfers electrical energy between two or more circuits through electromagnetic induction. Electromagnetic induction produces an electromotive force across a conductor which is exposed to time varying magnetic fields. Commonly, transformers are used to increase or decrease the voltages of alternating current in electric power applications. Since the invention of the first constant potential transformer in 1885, transformers have become essential for the transmission, distribution, and utilization of alternating current electrical energy.[3] A wide range of transformer designs are encountered in electronic and electric power applications.

Electric generator U.S. NRC image of a modern steam turbine generator The reverse conversion of electrical energy into mechanical energy is done by an electric motor, and motors and generators have many similarities. Many motors can be mechanically driven to generate electricity and frequently make acceptable generators. History[edit] Before the connection between magnetism and electricity was discovered, electrostatic generators were used.