Faraday's law
Faraday's law of induction gives the relation between the rate of change of the magnetic flux through the area enclosed by a closed loop and the electric field induced along the loop:
-
where
E is the induced electric field, d
s is an
infinitesimal element of the closed loop and dΦ
B/dt is the rate of change of the magnetic flux. Or, in differential form in terms of
magnetic field B:
In the case of an
inductor coil where the electric wire make N turns, the formula becomes:
-
where
V is the induced
electromotive force and ΔΦ/Δt denote the change of magnetic flux Φ during the time interval Δt. The direction of the electromotive force (the negative sign in the above formula) was first given by the
Lenz's law.
Faraday's law, along with the other laws of electromagnetism, was later incorporated into Maxwell's equations, unifying all of electromagnetism.
See also electromagnetic induction.