# Magnetic Constant

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## magnetic constant

[mag′ned·ik ′kän·stənt] (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 μ_{0}.## Magnetic Constant

a proportionality constant μ_{0} which occurs in a number of formulas involving magnetism when they are written in rationalized form (in the International System of Units). Thus, the induction B and intensity H of a magnetic field are related in a vacuum by the formula B = μ_{o}H, where μ_{0} = 4π ×10^{-7} henry sperm (H/m) ≈ 1.26 ×10^{-6} H/m.