The ratio of the orbital magnetic moment to the orbital angular momentum is the gyromagnetic ratio: \(\frac{\mu_L}{L} = \frac{e}{2m_e}\). The quantum of magnetic moment defined this way is the Bohr magneton: \(\mu_B = \frac{e\hbar}{2m_e} = 9.274 \times 10^{-24}\ \text{J/T}\). It is the natural unit of atomic magnetic dipole moments.