In electromagnetism, permeance is the inverse of reluctance. Permeance is a measure of the quantity of flux for a number of current-turns in magnetic circuit. A magnetic circuit almost acts as though the flux is 'conducted', therefore permeance is larger for large cross sections of a material and smaller for longer lengths. This concept is analogous to electrical conductance in the electric circuit.
Magnetic permeance is defined as the reciprocal of magnetic reluctance (in analogy with the reciprocity between electric conductance and resistance):
which can also be re-written:
ΦB = Magnetic flux
NI = Current-turns, (current) × (number of turns of conductor to make a coil).
Alternatively in terms of magnetic permeability (analogous to electric conductance):
μ = Permeability of material
A = Cross-sectional area
= magnetic path length
The SI unit of magnetic permeance is "webers per ampere-turn", that is H (henry).
In Materials science, permeance is the degree to which a material transmits another substance.
External articles and references
- Properties of Magnetic Materials (units of magnetic permeance)
- Bombaru, D., Jutras, R., and Patenaude, A., "Air Permeance of Building Materials". Summary report prepared by, AIR-INS Inc. for Canada Mortgage and Housing Corporation, Ottawa, 1988.