What do you understand by reluctance?

Magnetic reluctance, or magnetic resistance, is a concept used in the analysis of magnetic circuits. It is analogous to resistance in an electrical circuit, but rather than dissipating electric energy it stores magnetic energy. In likeness to the way an electric field causes an electric current to follow the path of least resistance, a magnetic field causes magnetic flux to follow the path of least magnetic reluctance. It is a scalar, extensive quantity, akin to electrical resistance. The units for magnetic reluctance are inverse Henries, H^–1.

In a DC field, the reluctance is the ratio of the "magnetomotive force” (MMF) in a magnetic circuit to the magnetic flux in this circuit. In a pulsating DC or AC field, the reluctance is the ratio of the amplitude of the "magnetomotive force” (MMF) in a magnetic circuit to the amplitude of the magnetic flux in this circuit.. (see phasors)

The definition can be expressed as follows:

where

("R") is the reluctance in ampere-turns per weber (a unit that is equivalent to turns per henry). "Turns" refers to the winding number of an electrical conductor comprising an inductor.

("F") is the magnetomotive force (MMF) in ampere-turns

F ("Phi") is the magnetic flux in webers.

It is sometimes known as Hopkinson's law and is analogous to Ohm's Law with resistance replaced by reluctance, voltage by MMF and current by magnetic flux.