Magnetomotive force

In physics, the magnetomotive force is a quantity appearing in the equation for the magnetic flux in a magnetic circuit, sometimes known as Hopkinson's law. It is the property of certain substances or phenomena that give rise to magnetic fields:

where Φ is the magnetic flux and R is the reluctance of the circuit. It can be seen that the magnetomotive force plays a role in this equation analogous to the voltage V in Ohm's law: V = IR, since it is the cause of magnetic flux in a magnetic circuit:

1. ℱ = NI where N is the number of turns in the coil and I is the electric current through the circuit. Sometimes the unit of gilbert is used to express ℱ.
2. ℱ = ΦR where Φ is the magnetic flux and R is the reluctance
3. ℱ = HL where H is the magnetizing force (the strength of the magnetizing field) and L is the mean length of a solenoid or the circumference of a toroid