Permeability of free space, abbreviated as \( \mu_0 \) (Greek symbol mu), also known as the magnetic constant, is a fundamental physical constant that describes how magnetic fields form and interact in a perfect vacuum. It represents the degree to which free space can support the creation of magnetic field lines and determines the strength of the magnetic interaction between currents or magnetic sources when no material medium is involved. μ₀ is essential in electromagnetism, appearing in Ampère’s law, the Biot–Savart law, and the relationship that defines the speed of light. Its exact value is \(\;4\pi \;x\; 10^{-7} H/m\), which helps quantify how magnetic fields propagate and behave in free space, forming one of the foundational constants in electromagnetic theory.
