Spins wobble (or precess) about the axis of the BO field so as to describe a cone. This is called precession. Spinning protons are like dreidles spinning about their axis. Precession corresponds to the gyration of the rotating axis of a spinning body about an intersecting axis.

 

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The resonance frequency, called Larmor frequency (ω0) or precessional frequency, is proportional to the main magnetic field strength: ω0 = γ B0.

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