Original: 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 .
Simplified: what is the direction of this induced emf ? Lenz 's law tells us immediately that it must be counterclockwise , so as to oppose the building up of the current .