Magnetic reluctance is the ratio of the amplitude of the magneto-motive force (MMF) in an electrical circuit to the amplitude of the magnetic flux in this circuit.
L = Length of circuit A = Cross-sectional area of the circuit μ = Permeability of vacuum(4 π 10 -7 N A-2) μo = Relative magnetic permeability
Consider a steel with the mean length of 20 m, the cross section of 2 m2. What is the Magnetic reluctance ?
Length of circuit = 20 Cross-sectional area = 2 Permeability of steel = 875 *10 -6
Substitute the given values in the formula,
|Magnetic reluctance (R)||= L / A μ μ0|
|= 20/2 x 4 x 3.14 x 10-7 x 875 x 10-6|
|= 20/21980 x 10-13|
|= 0.0087 At/Wb|