The Bohr magneton (symbol μ_B) is named after the physicist Niels Bohr. It is a physical constant of magnetic moment, defined by:

where:

e is the elementary charge,

is the reduced Planck's constant,

m_e is the electron rest mass

In the SI system of units its value is approximately:

μ_B = 9.274 008 99(37) × 10^-24 J·T^-1

The Bohr magneton is the natural unit for expressing the electron magnetic dipole moment.

See also

• Physical constant