i m = Φ Φ ˙ ˙ = d d t ∫ ∫ S B ⋅ ⋅ d S The resistance–reluctance model uses a different equivalence, taking magnetic current to be an alternate name for flux, Φ Φ . This difference in the definition of magnetic current is the fundamental difference between the gyrator-capacitor model and the resistance–reluctance model. The definition of magnetic current and magnetic voltage imply the definitions of the other magnetic elements.