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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. 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 is the electromotive force (EMF) and ΦB is the magnetic flux. the EMF on a wire loop is: Related:  DIY Clean Energy

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. History[edit] Alternating current generating systems were known in simple forms from the discovery of the magnetic induction of electric current in the 1830s. Principle of operation[edit] Diagram of a simple alternator with a rotating magnetic core (rotor) and stationary wire (stator) also showing the current induced in the stator by the rotating magnetic field of the rotor. The rotating magnetic field induces an AC voltage in the stator windings. An automatic voltage control device controls the field current to keep output voltage constant. In short, a conductor moving relative to magnetic field has an induced EMF in it(Faraday's Law).

Electromagnetic radiation The electromagnetic waves that compose electromagnetic radiation can be imagined as a self-propagating transverse oscillating wave of electric and magnetic fields. This diagram shows a plane linearly polarized EMR wave propagating from left to right. The electric field is in a vertical plane and the magnetic field in a horizontal plane. The two types of fields in EMR waves are always in phase with each other with a fixed ratio of electric to magnetic field intensity. Electromagnetic radiation (EM radiation or EMR) is a form of radiant energy, propagating through space via electromagnetic waves and/or particles called photons. In classical physics, EMR is considered to be produced when charged particles are accelerated by forces acting on them. EMR carries energy—sometimes called radiant energy—through space continuously away from the source (this is not true of the near-field part of the EM field). Physics[edit] Theory[edit] Maxwell’s equations for EM fields far from sources[edit]

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... 2 plastic triangles sized to match the width of the magnet your using, 1 magnet, some small wooden dowl, 2 1/4" round steel stock ( cut bolts work well ), and some 1/4" bar stock that closely matches the thickness and width of the magnet your using. Next you'll wind 3 coils that will fit around the frame... I used 100 turns of #28 wire as an experiment and it worked pretty well but you can adjust the amount of turns you want based on the voltage you need. Lay the 3 coils over the triangles and tape the coils together. Below is a picture of the completed unit... It easily lights LED's as well has the ability to charge nicad batteries... give it a spin ! Want more? Here is a shot of the parts you'll need to make... The layout and drilling is easy if you make a pattern and tape it to the plastic.

Electromagnetic field The field can be viewed as the combination of an electric field and a magnetic field. The electric field is produced by stationary charges, and the magnetic field by moving charges (currents); these two are often described as the sources of the field. The way in which charges and currents interact with the electromagnetic field is described by Maxwell's equations and the Lorentz force law. From a classical perspective in the history of electromagnetism, the electromagnetic field can be regarded as a smooth, continuous field, propagated in a wavelike manner; whereas from the perspective of quantum field theory, the field is seen as quantized, being composed of individual particles.[citation needed] Structure of the electromagnetic field[edit] The electromagnetic field may be viewed in two distinct ways: a continuous structure or a discrete structure. Continuous structure[edit] Classically, electric and magnetic fields are thought of as being produced by smooth motions of charged objects.

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. Transformers range in size from RF transformers less than a cubic centimeter in volume to units interconnecting the power grid weighing hundreds of tons. Basic principles[edit] Ideal transformer[edit] Ideal transformer equations (eq.) By Faraday's law of induction . . . (1)[a] Combining ratio of (1) & (2) Turns ratio

Electrical resistance An object of uniform cross section has a resistance proportional to its resistivity and length and inversely proportional to its cross-sectional area. All materials show some resistance, except for superconductors, which have a resistance of zero. The resistance (R) of an object is defined as the ratio of voltage across it (V) to current through it (I), while the conductance (G) is the inverse: may be most useful; this is called the "differential resistance". Introduction[edit] The hydraulic analogy compares electric current flowing through circuits to water flowing through pipes. In the hydraulic analogy, current flowing through a wire (or resistor) is like water flowing through a pipe, and the voltage drop across the wire is like the pressure drop that pushes water through the pipe. The voltage drop (i.e., difference in voltage between one side of the resistor and the other), not the voltage itself, provides the driving force pushing current through a resistor. Ohm's law[edit] where .

How to Build Your Own Uninterruptible Power Supply Edit Article Edited by Evildave, Brandywine, Jonathan E., MBD123 and 15 others In the event of extended blackout, you may have critical systems (such as computer or medical equipment) that must remain running no matter what. Most uninterrupted power supplies sold for computers 'switch' power, running a small inverter when power is interrupted, then switching back to 'normal' power when it's back on. Ad Steps 1Read all warnings before proceeding. 13Supplement alternatives where beneficial or necessary. Warnings Do not wear watches or jewelry when working on the batteries.Wear eye protection when working on batteries.Grounding the inverter is not optional, it is a must.

Permittivity A dielectric medium showing orientation of charged particles creating polarization effects. Such a medium can have a higher ratio of electric flux to charge (permittivity) than empty space In electromagnetism, absolute permittivity is the measure of the resistance that is encountered when forming an electric field in a medium. In other words, permittivity is a measure of how an electric field affects, and is affected by, a dielectric medium. The permittivity of a medium describes how much electric field (more correctly, flux) is 'generated' per unit charge in that medium. More electric flux exists in a medium with a high permittivity (per unit charge) because of polarization effects. In SI units, permittivity ε is measured in farads per meter (F/m); electric susceptibility χ is dimensionless. where εr is the relative permittivity of the material, and ε0 = 8.8541878176.. × 10−12 F/m is the vacuum permittivity. Explanation[edit] Vacuum permittivity[edit] Its value is[1] where If