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Lenz's law is a common way of understanding how electromagnetic circuits obey Newton's third law and the conservation of energy.〔Schmitt, Ron. (''Electromagnetics explained'' ). 2002. Retrieved 16 July 2010.〕 Lenz's law is named after Heinrich Lenz, and it says: If an induced current flows, its direction is always such that it will oppose the change which produced it. Lenz's law is shown with the negative sign in Faraday's law of induction: : which indicates that the induced voltage (ℰ) and the change in magnetic flux (∂Φ) have opposite signs. Lenz's Law is a qualitative law that refers to the direction of induced current in relation to the effect which produces it without quantitatively relating their magnitudes. For a rigorous mathematical treatment, see electromagnetic induction and Maxwell's equations. ==Opposing currents== If a change in the magnetic field of current ''i''1 induces another electric current, ''i''2, the direction of ''i''2 is opposite that of the change in ''i''1. If these currents are in two coaxial circular conductors ''ℓ''1 and ''ℓ''2 respectively, and both are initially 0, then the currents ''i''1 and ''i''2 must counter-rotate. The opposing currents will repel each other as a result. Lenz's law states that the current induced in a circuit due to a change or a motion in a magnetic field is so directed as to oppose the change in flux and to exert a mechanical force opposing the motion. 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「Lenz's law」の詳細全文を読む スポンサード リンク
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