Current in the windings induces a magnetic flux that is guided by the core material, which is characterized by its permeability. If current in the windings is interpreted as a source driving a flow property, the magnetic flux, then it is possible to define a kind of resistance of the magnetic conduction path, called reluctance, Rm. An inductor with an air gap can be modelled as a magnetic reluctance circuit coupled with an electric circuit. The dependency of the reluctance model on the core material and core geometry is shown in the applet.

• Drag the red point to change the number of windings. This has a direct impact on the inductivity but no influence on the core reluctances.
• Drag the red point to change the cross section area Ae of the magnetic core. With smaller cross section area Ae the core reluctances Rm,i will increase, and flux and inductivity will be reduced.
• Increasing the air gap will increase the according air gap reluctance and reduce the inductivity.
• Drag the red point to change the permeability of the magnetic core material. This will have only a small effect on the inductivity because the air gap provides the dominating reluctance.