# Magnetomotive Force

**Definition:** The current flowing in an electric circuit is due to the existence of electromotive force similarly **magnetomotive force** (MMF) is required to drive the magnetic flux in the magnetic circuit. The magnetic pressure, which sets up the magnetic flux in a magnetic circuit is called Magnetomotive Force. The SI unit of MMF is Ampere-turn (AT), and their CGS unit is G (gilbert). The MMF for the inductive coil shown in the figure below is expressed as

Where, N – numbers of turns of inductive coil

I – current

The strength of the MMF is equivalent to the product of the current around the turns and the number of turns of the coil. As per work law, The MMF is defined as the work done in moving the unit magnetic pole (1weber) once around the magnetic circuit.

The MMF is also known as the magnetic potential. It is the property of material to give rise the magnetic field. The magnetomotive force is the product of the magnetic flux and the magnetic reluctance. The reluctance is the opposition offers by the magnetic field to set up the magnetic flux on it. The MMF regarding reluctance and magnetic flux is given as

Where R – reluctance

Φ – magnetic flux

The magnetomotive force can measure regarding magnetic field intensity and the length of the substance. The magnetic field strength is the force act on the unit pole placed on the magnetic field. MMF regarding field intensity is expressed as

Where H is the magnetic field strength, and l is the length of the substance.