Lenz's law is a common way of understanding how electromagnetic circuits must always obey Newton's third law. Lenz's law is named after Heinrich Lenz, and it says:
"An induced current is always in such a direction as to oppose the motion or change causing it."
Faraday's law of induction indicates that the induced electromotive force (emf) and the change in flux have opposite signs, and it also gives the direction of the induced (emf) and current resulting from electromagnetic induction.
For a rigorous mathematical treatment, see electromagnetic induction and Maxwell's equations.
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