We can find the relationship between the field in which the precession occurs and the precession frequency by applying a field such that it seems as though the Earth’s field has increased. This is done by using Helmholtz coils to apply a field which artificially increases Earth’s field. We increase the current in the coils from 0.02 A to 0.17 A, corresponding to increasing the field from \(1.78~\mu T\) to \(15.1~\mu T\) (as the coils have a coil constant of \(89~\mu T/A\)). We tune the bandpass filter frequency range as we go along because the amplitude of the precession on the oscilloscope will be greatest when the resonant frequency of the circuit within the instrument coincides with the Larmor precession frequency. So, as our precession frequency changes with magnetic field, we must adjust the resonant frequency of the circuit to obtain a good signal. We optimize using coarse and fine tuning and observing when the amplitude is greatest on the oscilloscope. Once the resonant frequency has been optimized, we can record the precession frequency. We go through this process each time we change the field, and then plot precession frequency vs field (shown in Fig. \ref{fig:precession}).