Magnetoelectric induction [1] is the phenomenon of excitement of the electromotive force (EMF) of induction in contour as a result of change of magnetic flux (or magnetic flux linkage) across surface, bounded by this contour, because of change of magnetic field itself or motion of the contour (of electroconductor, dielectric or another body) in the stationary magnetic field.
The phenomenon of “magnetoelectric induction", together with the phenomenon of “induction of electric currents" (the “electric mutual induction" phenomenon – in contemporary terminology) was discovered by Michael Faraday 29 August 1831 [1] (and independently in this same year by J. Genry – also in the form of “magnetoelectric phenomenon", which was published later – in 1832 [2]). Faraday found that the electromotive force (EMF), produced along a closed path, is proportional to the rate of change of the magnetic flux through surface, bounded by that path. In practice, this means that an electric current will flow in any closed conductor, when the magnetic flux through a surface, bounded by the conductor, changes. This applies whether the field itself changes in strenght or the conductor is moving through the external magnetic field, across it.
“Magnetoelectric Induction" (Faraday, 1831), together with other fundamental phenomenon – “Electrodynamic Force" (Ampere, 1820), lie in the basis of principle of operation of “electric inductive machines" with magnetic field of excitation (electric generators and motors, electric transformers) and many other induction devices and apparatus.
The quantitative representation of the phenomenon of magnetoelectric induction is in form of Faraday’s law of induction (or Law of magnetoelectric induction), which consist in such a manner, that the produced EMF of magnetoelectric induction in a contour is quantitatively equal and opposite in sign to the rate of change of magnetic flux (or magnetic flux linkage) across surface, bounded by this contour.
In the formulation of Faraday for the law of magnetoelectric induction the electromotive force, induced in the contour, is equal to the rate of cross of the contour by the individual lines of magnetic induction, taken with the opposite sign. For closed contours the formulations of Maxwell and Faraday are identical.
Further, Lentz’s Law (1833) [3] gives Rule of Lentz for the direction of the induced EMF, thus:
“The EMF induced in an electric circuit always acts in such a direction that the current it drives around the circuit opposes the change in magnetic flux, which produces the EMF".
It, accordingly, demand for the opposite sign in the above-presented relations, which in result may be both “–" and “+", in dependence from accepted conditional directions.
As a result, the direction of the induced EMF and current in a conductor, dielectric or another body, moving in magnetic field across to the force lines, is determined by the mnemonic “rule of a right hand" or the strength induced electric field determined by the vector product (in agreed-upon rightwinding system of co-ordinates) [according to Maxwell’s equation (1862) for media, moving in a magnetic field, and to its modifications in the form of Heaviside’s expressions (1885 and 1889), the equations of Maxwell-Hertz (1890) and Lorentz’s formula (1892)]:
E = [v B]
The term “magneto-electric induction" or “magnelectric induction" (1831) [1], which from the outset has been applied by Faraday for the given phenomenon, presents such natural fact, that a varying magnetic field – the cause, and a originated electric field – the consequence.
The dual-symmetric induction phenomenon, in which a varying electric field – the cause, and a originated magnetic field – the consequence, is the phenomenon of “electromagnetic induction" {in the natural interpretation (1980) [4], which is substantiated physically, terminologically and in a sense}.
References
[1] Faraday M. Experimental Researches in Electricity [Ser. 1, pt. 2. Evolution of electricity from magnetismus] // Philosoph. Trans. of the Royal Soc., 1832, p. 133-145.
[2] Henry J. On the production of currents and sparks from magnetism // American Journal of Science, 1832, vol. 22, p. 403-408.
[3] Lentz E. Ch. Über die Bestimmung der Richtung der durch elektrodynamische Verteilung erregten galvanischen Ströme. – Ann. d. Phys. u. Chem., Leipzig, 1834, Bd. XXXI, S. 483-494.
[4] Sidorovich A. M., Electromagnetic Induction (New Conception). -- Proc. Int. Symp. (ISEF’87), Pavia, Italy, September 1987, p. 25-27.
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