The work that would be required to carry a hypothetical isolated magnetic pole of unit strength completely around a magnetic circuit.
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The work that would be required to carry a hypothetical isolated magnetic pole of unit strength completely around a magnetic circuit.
The magnetomotive force (mmf) around a magnetic circuit is the work per unit magnetic pole required to carry the pole once around the circuit. It is the analog of electromotive force.
It is expressed mathematically in the equation below,
where H cos θ is the component of magnetic field strength in the direction of a length of path ds. The line integral is taken around any closed path in the field.
Maximal midexpiratory flow (rate).
Magnetomotive force is any physical cause that produces magnetic flux. It is analogous to electromotive force or voltage in electricity.
In this context, the word "force" is used in a general sense of "that which has a physical effect", and is not the same as mechanical force measured in newtons.
The standard definition of magnetomotive force involves current passing through an electrical conductor, which accounts for the magnetic fields of electromagnets as well as planets and stars. Permanent magnets also exhibit magnetomotive force, but for different reasons.
The unit of magnetomotive force is the ampere-turn (At), represented by a steady, direct electric current of one ampere flowing in a single-turn loop of electrically conducting material in a vacuum.
The gilbert (Gi), established by the IEC in 1930 [1], is the CGS unit of magnetomotive force. The gilbert is defined differently, and is a slightly smaller unit than the ampere-turn. The unit is named after William Gilbert (1544 - 1603) English physician and natural philosopher.

The magnetomotive force
in an inductor is given by:

where N is the number of turns of the coil, I is the current in the coil, Φ is the magnetic flux and
is the
reluctance of the magnetic circuit.
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