Magnetomotive Force (M.M.F.or F)

Magnetomotive Force (M.M.F.or F)

 • The flow of electrons is current which is basically due to electromotive force (e.m.f.). Similarly the force behind the flow of flux or production of flux in a magnetic circuit is called magnetomotive force (m.m.f.) The m.m.f. determines the magnetic field strength.

 • It is the driving force behind the magnetic circuit. It is given by the product of the number of turns of the magnetizing coil and the current passing through it. Mathematically it can be expressed as,

m. m. f. = NI ampere turns

where N = Number of turns of magnetising coil and

I = Current through coil Its unit is ampere turns (AT) or amperes (A).

• It is also defined as the work done in joules on a unit magnetic pole in taking it once round a closed magnetic circuit.

Review Question  

1. Define magnetomotive force and state its units.