First we put the child on the carousel holding the bar magnet and the electrically charged ball. We put the magnetometer in the center of the carousel. Before the ride on the carousel starts, there is allready a B_dip contribution due to the bar magnet, once the carousel starts moving there is also the B_orb contribution due to the moving electrical ball. In fact there are only these two contributions, however I was thinking about the following:
If we would have a brush (I do not know how to translate exactly to englisch but I mean ‘de kwast’/’de floche’) and we imagine that there are electrons on this brush (with different number of up and down spins), and this brush is everytime moved in the radial direction of the carousel and thus sometimes is in the center of the carousel (where the nucleus is) and thus this could give a B_fermi contribution?