Question 32.19: Protons precess at a frequency of 42.6 MHz in an external fi...

a Rearrange f_{0} = \frac{γB_{0}}{2π} to give gyromagnetic ratio
γ = \frac{2πf_{0}}{B_{0}} = \frac{2  ×  π  ×  42.6  ×  10^{6}}{1.0} = 2.68 × 10^{8}  Hz  T^{–1}
For a field of 2.5 T, f_{0} = \frac{γB_{0}}{2π}

= \frac{2.68  ×  10^{8}  ×  2.5}{2  ×  π} = 106.5  MHz
b This is also their resonant frequency (106.5 MHz).