Reluctance

As the property which opposes the flow of electric current in an electrical circuit is called resistance , so the property which opposes the flow of magnetic lines of force in a magnetic circuit is called reluctance . In the case of the electric circuit, the resistance is the reciprocal of the conductivity; in the case of the magnetic circuit, the reluctance is the reciprocal of the permeability. As in the case of an electrical circuit, the amount of flow of current is equal to the electromotive force divided by the resistance; so in a magnetic circuit, the magnetic flux is equal to the magnetizing force or magnetomotive force divided by the reluctance. IMG:384091999325875926_fig090_t.gif.png:Illustration_ Fig. 90. Bar Electromagnet Fig. 90. Bar Electromagnet View full size illustration.