magnetic constant

(electromagnetism) The absolute permeability of empty space, equal to 1 electromagnetic unit in the centimeter-gram-second system, and to 4π × 10^-7 henry per meter or, numerically, to 1.25664 × 10^-6 henry per meter in the International System of units. Symbolized μ₀.

electromagnetics. Symbol μ₀. SI The adopted value for the magnetic permeability (see permittivity) of a vacuum = 4π × 10^-7 H·m^-1 = 1.256 6~ × 10^-6 N·A^-2.