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6: Magnetic circuit analog to electric circuits

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    Introduction

    In this chapter we describe an equivalence between electric and magnetic circuits and in turn a method of describing and analyzing magnetic field systems which can be described in magnetic circuit fashion. As it turns out, the equivalence is a fair approximation to reality and may be used with some confidence.

    Magnetic circuits are those parts of devices that employ magnetic flux to either induce voltage or produce force. Such devices include transformers, motors, generators and other actuators (including things such as solenoid actuators and loudspeakers). In such devices it is necessary to produce and guide magnetic flux. This is usually done with pieces of ferromagnetic material (which has permeability very much larger than free space). In this sense, magnetic circuits are like electric circuits in which conductive material such as aluminum or copper has high electric conductivity and are used to guide electric current.

    The analogies between electric and magnetic circuits are two: the electric circuit quantity of current is analogous to magnetic circuit quantity flux. (Both of these quantities are ’solenoidal’ in the sense that they have no divergence). The electric circuit quantity of voltage, or electomotive force (EMF) is analogous to the magnetic circuit quantity of magnetomotive force (MMF). EMF is the integral of electric field \(\ \vec{E}\), MMF is the integral of magnetic field \(\ \vec{H}\).

    This page titled 6: Magnetic circuit analog to electric circuits is shared under a CC BY-NC-SA 4.0 license and was authored, remixed, and/or curated by James Kirtley (MIT OpenCourseWare) via source content that was edited to the style and standards of the LibreTexts platform; a detailed edit history is available upon request.