Permeance

Permeance, in general, is the degree to which a material admits a flow of matter or energy. Permeance is usually represented by a curly capital P: ${\displaystyle {\mathcal {P}}}$.

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 ${\displaystyle {\mathcal {P}}}$ is defined as the reciprocal of magnetic reluctance ${\displaystyle {\mathcal {R}}}$ (in analogy with the reciprocity between electric conductance and resistance):

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