i) MMF: It is the force that drives magnetic flux through magnetic circuit. It is measured in amp-turns.
ii) Reluctance (s) :- Reluctance is the property of the substance which opposes the creation of flux in it.
iii) Fringing: When the magnetic flux passing or crossing an air gap then it tends to bulge outwards the iron ring, this effect is called as “Fringing”.
iv) Leakage flux: Some flux while passing through the magnetic circuit, leaks through the air surrounding the core. This flux is called as leakage flux.