Magnetic Circuit

Also found in: Dictionary, Wikipedia.

magnetic circuit

[mag′ned·ik ′sər·kət]
A group of magnetic flux lines each forming a closed path, especially when this circuit is regarded as analogous to an electric circuit because of the similarity of its magnetic field equations to direct-current circuit equations.
McGraw-Hill Dictionary of Scientific & Technical Terms, 6E, Copyright © 2003 by The McGraw-Hill Companies, Inc.
The following article is from The Great Soviet Encyclopedia (1979). It might be outdated or ideologically biased.

Magnetic Circuit


a series of magnetic materials through which a magnetic flux passes. The concept is extensively used in the design of electrical machines, transformers, permanent magnets, electromagnets, relays, magnetic amplifiers, and electrical measuring instruments. In technology extensive use is made of magnetic circuits in which virtually the entire magnetic flux passes through ferromagnetic bodies (closed magnetic circuits), as well as circuits that include diamagnetic mediums, such as air gaps, along with the ferromagnetic materials. If the flux in a magnetic circuit is excited by permanent magnets, the circuit is called a polarized circuit. Circuits without permanent magnets are called neutral, and the magnetic flux in them is excited by a current flowing through windings that surround part or all of the magnetic circuit.

A distinction is made among magnetic circuits with constant, alternating, and pulsed magnetic fluxes, depending on the nature of the excitation current. As a result of the complete formal analogy between electrical and magnetic circuits, they have a common mathematical treatment. For example, the analogue of Ohm’s law for a magnetic circuit is the formula F = Φ.Rm, where Φ is the magnetic flux, Rm is the magnetic resistance, and Fis the magnetomotive force. Kirchhoff’s laws are applicable to magnetic circuits. However, there is a major difference between the two types of circuits. A flux Φ in a magnetic circuit that does not vary with time produces no heating effect—that is, no electromagnetic energy is dissipated.


Kalashnikov, S. G. Elektrichestvo. Moscow, 1956. (Obshchii kurs fiziki, vol. 2.)
Polivanov, K. M. Ferromagnetiki. Moscow-Leningrad, 1957.
The Great Soviet Encyclopedia, 3rd Edition (1970-1979). © 2010 The Gale Group, Inc. All rights reserved.
References in periodicals archive ?
Figure 3 shows an substitution circuit of the magnetic circuit of a double-rod electromagnet used in the vast majority of vacuum and low voltage contactors.
During the optimization of the magnetic circuit of the studied SRM performed within this study, only inequality limitations were applied.
The magnetic circuit is constituted by the coil, which is the magnetic flux source, and the flux path.
The torque production in the switched reluctance motor is because of the tendency of the magnetic circuit to adopt the configuration of minimum reluctance i.e.
Nonlinear varying-network magnetic circuit analysis for doubly salient permanent-magnet motors [J].
The magnetic force of attraction between magnet and plates can be explained using magnetic circuit analysis [4].
These manipulations lead to the specification of all dimensions of the machine and analysis of the magnetic circuit of the generator.
Loudspeakers larger than earphones have a narrow space between the voice coil and the magnetic circuit, making it very likely that air viscosity has a significant impact and is a factor of estimation errors of the sound pressure frequency.
For the HSV, the functional relationship between the total magnetic flux and the total reluctance of the magnetic circuit is described as
The design engineers at SG Transmission were also faced with the challenge of designing an efficient magnetic circuit to fit in such a small envelope, which incorporated the coil to deenergise the brake.