Faraday’s Law . It is based on the experiments carried out by Michael Faraday in England in 1831 and by Joseph Henry in the United States at almost the same time. Faraday published his results first, which gives him the priority of discovery.

## Summary

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• 1 Faraday’s law of induction
• 2 Considerations
• 4 Source

Imagine that there are two lines of a magnetic field coming from a magnet and from a current loop that some of those field lines pass through a coil, when you move the magnet or open or close the switch the number of lines of the magnetic field passing through the coil changes. As Faraday’s experiments demonstrated, and since Faraday’s field line technique helps perceive, what induces the electromotive force (emf) in the ring is the change in the number of field lines that pass through a closed circuit. Specifically, what determines the induced emf is the rate of change in the number of field lines that pass through the ring, thereby establishing that the induced voltage in aClosed circuit is directly proportional to the speed with which the magnetic flux that passes through any surface with the circuit as edge changes in time:

Where E is the electric field, dl is an infinitesimal element of the contour C, B is the density of magnetic field and S is an arbitrary surface, which edge is C. addresses contour C and dA are given by the Rule right hand.

The permutation of the surface integral and the time derivative can be done as long as the integration surface does not change over time.

By means of Stokes’ Theorem, a differential form of this law can be obtained:

This is one of Maxwell’s Equations , which make up the fundamental equations of Electromagnetism . Faraday’s law, along with the other laws of Electromagnetism, was incorporated into Maxwell’s equations, thus allowing electromagnetism to be unified. In the case of an inductor with N turns of wire, the previous formula is transformed into:

where  is the induced voltage and dΦ / dt is the rate of change of the magnetic flux over time Φ . The induced voltage direction (the negative sign in the formula) is due to Lenz’s Law .

## Considerations

It should be noted that even though the equation is known as Faraday’s law, it was not written that way by Faraday, who lacked a Mathematical background . In fact, the three-volume work that Faraday published on Magnetism , and which constitutes a milestone in the development of Physics and Chemistry, does not contain a single equation