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Faraday's law of induction is a basic law of electromagnetism predicting how a magnetic field will interact with an electric circuit to produce an electromotive force (EMF)—a phenomenon called electromagnetic induction. It is the fundamental operating principle of transformers, inductors, and many types of electrical motors, generators and solenoids.〔(【引用サイトリンク】title=Applications of electromagnetic induction )〕 The Maxwell–Faraday equation is a generalization of Faraday's law, and forms one of Maxwell's equations. ==History== Electromagnetic induction was discovered independently by Michael Faraday in 1831 and Joseph Henry in 1832. Faraday was the first to publish the results of his experiments.〔(【引用サイトリンク】title=Joseph Henry )〕 In Faraday's first experimental demonstration of electromagnetic induction (August 29, 1831), he wrapped two wires around opposite sides of an iron ring or "torus" (an arrangement similar to a modern toroidal transformer). Based on his assessment of recently discovered properties of electromagnets, he expected that when current started to flow in one wire, a sort of wave would travel through the ring and cause some electrical effect on the opposite side. He plugged one wire into a galvanometer, and watched it as he connected the other wire to a battery. Indeed, he saw a transient current (which he called a "wave of electricity") when he connected the wire to the battery, and another when he disconnected it.〔''Michael Faraday'', by L. Pearce Williams, p. 182-3〕 This induction was due to the change in magnetic flux that occurred when the battery was connected and disconnected.〔 Within two months, Faraday had found several other manifestations of electromagnetic induction. For example, he saw transient currents when he quickly slid a bar magnet in and out of a coil of wires, and he generated a steady (DC) current by rotating a copper disk near the bar magnet with a sliding electrical lead ("Faraday's disk").〔''Michael Faraday'', by L. Pearce Williams, p. 191–5〕 Michael Faraday explained electromagnetic induction using a concept he called lines of force. However, scientists at the time widely rejected his theoretical ideas, mainly because they were not formulated mathematically.〔''Michael Faraday'', by L. Pearce Williams, p. 510〕 An exception was James Clerk Maxwell, who used Faraday's ideas as the basis of his quantitative electromagnetic theory.〔〔Maxwell, James Clerk (1904), ''A Treatise on Electricity and Magnetism'', Vol. II, Third Edition. Oxford University Press, pp. 178–9 and 189.〕〔("Archives Biographies: Michael Faraday", The Institution of Engineering and Technology. )〕 In Maxwell's papers, the time-varying aspect of electromagnetic induction is expressed as a differential equation which Oliver Heaviside referred to as Faraday's law even though it is different from the original version of Faraday's law, and does not describe motional EMF. Heaviside's version (see Maxwell–Faraday equation below) is the form recognized today in the group of equations known as Maxwell's equations. Lenz's law, formulated by Heinrich Lenz in 1834, describes "flux through the circuit", and gives the direction of the induced EMF and current resulting from electromagnetic induction (elaborated upon in the examples below). 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Faraday's law of induction」の詳細全文を読む スポンサード リンク
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