<P> This is similar to the equation for electrical resistance in materials, with permeability being analogous to conductivity; the reciprocal of the permeability is known as magnetic reluctivity and is analogous to resistivity . Longer, thinner geometries with low permeabilities lead to higher reluctance . Low reluctance, like low resistance in electric circuits, is generally preferred . </P> <P> The following table summarizes the mathematical analogy between electrical circuit theory and magnetic circuit theory . This is mathematical analogy and not a physical one . Objects in the same row have the same mathematical role; the physics of the two theories are very different . For example, current is the flow of electrical charge, while magnetic flux is not the flow of any quantity . </P> <Table> Analogy between' magnetic circuits' and electrical circuits <Tr> <Th_colspan="3"> Magnetic </Th> <Th> </Th> <Th_colspan="3"> Electric </Th> </Tr> <Tr> <Th> Name </Th> <Th> Symbol </Th> <Th> Units </Th> <Th> </Th> <Th> Name </Th> <Th> Symbol </Th> <Th> Units </Th> </Tr> <Tr> <Td> Magnetomotive force (MMF) </Td> <Td> F = ∫ H ⋅ d ⁡ l (\ displaystyle (\ mathcal (F)) = \ int \ mathbf (H) \ cdot \ operatorname (d) \ mathbf (l)) </Td> <Td> ampere - turn </Td> <Td> </Td> <Td> Electromotive force (EMF) </Td> <Td> E = ∫ E ⋅ d ⁡ l (\ displaystyle (\ mathcal (E)) = \ int \ mathbf (E) \ cdot \ operatorname (d) \ mathbf (l)) </Td> <Td> volt </Td> </Tr> <Tr> <Td> Magnetic field </Td> <Td> </Td> <Td> ampere / meter </Td> <Td> </Td> <Td> Electric field </Td> <Td> </Td> <Td> volt / meter = newton / coulomb </Td> </Tr> <Tr> <Td> Magnetic flux </Td> <Td> Φ (\ displaystyle \ Phi) </Td> <Td> weber </Td> <Td> </Td> <Td> Electric current </Td> <Td> </Td> <Td> ampere </Td> </Tr> <Tr> <Td> Hopkinson's law or Rowland's law </Td> <Td> F = Φ R m (\ displaystyle (\ mathcal (F)) = \ Phi (\ mathcal (R)) _ (m)) </Td> <Td> ampere - turn </Td> <Td> </Td> <Td> Ohm's law </Td> <Td> E = I R (\ displaystyle (\ mathcal (E)) = IR) </Td> <Td> </Td> </Tr> <Tr> <Td> Reluctance </Td> <Td> R m (\ displaystyle (\ mathcal (R)) _ (m)) </Td> <Td> 1 / henry </Td> <Td> </Td> <Td> Electrical resistance </Td> <Td> </Td> <Td> ohm </Td> </Tr> <Tr> <Td> Permeance </Td> <Td> P = 1 R m (\ displaystyle (\ mathcal (P)) = (\ frac (1) ((\ mathcal (R)) _ (m)))) </Td> <Td> henry </Td> <Td> </Td> <Td> Electric conductance </Td> <Td> G = 1 / R </Td> <Td> 1 / ohm = mho = siemens </Td> </Tr> <Tr> <Td> Relation between B and H </Td> <Td> B = μ H (\ displaystyle \ mathbf (B) = \ mu \ mathbf (H)) </Td> <Td> </Td> <Td> </Td> <Td> Microscopic Ohm's law </Td> <Td> J = σ E (\ displaystyle \ mathbf (J) = \ sigma \ mathbf (E)) </Td> <Td> </Td> </Tr> <Tr> <Td> Magnetic flux density B </Td> <Td> </Td> <Td> tesla </Td> <Td> </Td> <Td> Current density </Td> <Td> J </Td> <Td> ampere / square meter </Td> </Tr> <Tr> <Td> Permeability </Td> <Td> μ </Td> <Td> henry / meter </Td> <Td> </Td> <Td> Electrical conductivity </Td> <Td> σ </Td> <Td> siemens / meter </Td> </Tr> </Table> <Tr> <Th_colspan="3"> Magnetic </Th> <Th> </Th> <Th_colspan="3"> Electric </Th> </Tr>

What is the magnetic equivalent of electrical conductivity