Magnetomotive Force

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magnetomotive force

[mag¦nēd·ō′mōd·iv ′fōrs]
The work that would be required to carry a magnetic pole of unit strength once around a magnetic circuit. Abbreviated mmf.

Magnetomotive Force


a quantity that characterizes the magnetic action of an electric current. The magnetomotive force is introduced in calculations of magnetic circuits by analogy with the electromotive force in electric circuits.

The magnetomotive force F is equal to the circulation of the vector of magnetic field intensity H through a closed circuit L that encompasses the electric currents generated by the magnetic field:

(in the International System of Units). Here HI is the projection of H onto the direction of the element of the integration circuit d I and n is the number of conductors (coils) carrying a current Ii that are encompassed by the circuit. The unit of magnetomotive force is the ampere (or ampere-turn) in the International System of Units and the gilbert in the cgs system of units (symmetrical); 1 A = (4π/10) Gb ~ 1.2566 Gb.