Larmor frequency

where ${\displaystyle {\vec {\tau }}}$ is the torque, ${\displaystyle {\vec {\mu }}}$ is the magnetic dipole moment, ${\displaystyle {\vec {J}}}$ is the angular momentum vector, ${\displaystyle {\vec {B}}}$ is the external magnetic field, ${\displaystyle \times }$ symbolizes the cross product, and ${\displaystyle \gamma }$ is the gyromagnetic ratio, which gives the proportionality constant between the magnetic moment and the angular momentum. The angular momentum vector ${\displaystyle {\vec {J}}}$ precesses about the external field axis with an angular frequency known as the Larmor frequency,