Lenz's Law and Magnetic Flux

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 …

…induced emf during the time that the change takes place. The mutual inductance of two neighboring circuits is defined as the ratio of the emf induced in one circuit to the rate of change of current in the other circuit. () The SI unit of mutual inductance is the henry, the same a the unit of self- inductance. The same value is obtained for a pair of coils, regardless of which coil is the starting point. ()