Gyromagnetic ratio for an isolated electron

Description

In physics, the gyromagnetic ratio (also sometimes known as the magnetogyric ratio in other disciplines) of a particle or system is the ratio of its magnetic momentum in an atom to its angular momentum, and it is often denoted by the symbol γ, gamma. Its SI unit is the radian per second per tesla (rad⋅s^−1⋅T^−1) or, equivalently, the coulomb per kilogram (C⋅kg^−1). Gives the proportionality constant between the magnetic moment and the angular momentum. The term “gyromagnetic ratio” is always used as a synonym for a different but closely related quantity, the g-factor. The g-factor, unlike the gyromagnetic ratio, is dimensionless.

An isolated electron has an angular momentum and a magnetic moment resulting from its spin. While an electron’s spin is sometimes visualized as a literal rotation about an axis, it cannot be attributed to mass distributed identically to the charge. The above classical relation does not hold, giving the wrong result by a dimensionless factor called the electron g-factor.