 Larmor precession

Larmor precession is the precession of a magnetic moment about an applied magnetic field. For a spin with gyromagnetic ratio $\gamma$ and Hamiltonian $H=-\gamma \mathbf{B}\cdot \mathbf{S}$, its expectation obeys $d⟨\mathbf{S}angle/dt=\gamma ⟨\mathbf{S}angleimes\mathbf{B}$. A spin coherent state retains its coherent form during this rotation.

Larmor precession is the phenomenon in which the magnetic moment of a particle (such as an electron or nucleus) precesses around an external magnetic field. This occurs when a charged particle with a magnetic moment is placed in a magnetic field, causing the axis of the magnetic moment to rotate or "precess" around the direction of the applied field.

The equation is simple: frequency is proportional to field strength!