How does the reluctance of air in magnetic circuit compare with the resistance of air in electric circuit ?
Magnetic reluctance is analogous to electrical resistance, and is in units of At/W (Ampere turns per weber). There is an equivalent of Ohms law for magnetic circuits, where: Reluctance = Magneto Motive Force / magnetic flux Where: Reluctance is in units of ampere turns per weber. MMF is in ampere turns. magnetic flux is in webers.. Reluctance is proportional to LengthOfPath / Permeability x CrossSectionalArea. The permeability of air is 1, the permeability of magnetic materials up to a few thousand. Using realistic figures of 0.04m path and area of 0.0001m^2… Air, 40 Iron, 0.16 Therefore air is ~250 time the magnetic reluctance of iron. In the electrical case air is totally non conductive (except when it becomes ionised – breaks down). The resistance ratio between air and a metallic conductor approaches infinity.
