Lenz's Law and Faraday's Law of Induction 1. With this definition of the flux being , we can now return to Faraday's investigations. He found that the magnitude of the emf produced depends on the rate at which the magnetic flux changes. Faraday found that if the flux through N loops of wire changes by an amount , during a time delta t, the average induced emf during this time is This fundamental result is known as Faraday's law of induction. The minus sign is placed there to remind us in which direction the induced emf acts. Experiment shows that an induced emf