1. The problem statement, all variables and given/known data The nucleus of a Tl atom (Atomic mass = 203, element #81) has a magnetic moment of 1.611 µn. A magnetic field is applied to it and its NMR frequency determined to be 3.90 MHz. What is the magnitude of the magnetic field? 2. Relevant equations torque = magnetic moment x magnetic field radius = mv/qB v = rw Fcentripetal = mv^2/r 3. The attempt at a solution I tried (magnetic moment x magnetic field)/radius = mv^2/r but this always leaves me with r in the equation, which is unknown.