Spin angular momentum allows magnetic resonance phenomena to be explained via classical physics. When viewed from the reference frame attached to the rotating field, it seems that the magnetic dipole precesses around a net magnetic field ( Δ Δ ω ω z ^ ^ − − ω ω 1 X ^ ^ ) / γ γ , where z ^ ^ is the unit vector along uniform magnetic field B 0 and X ^ ^ is the same in the direction of rotating field B 1 and δ δ ω ω = ω ω − − ω ω 0 .