Comments for the explanation table  I think the explanation table is somewhat misleading when it terms that it if both disk and indicator are moving the result is undetermined It is surely not undetermined Like some strange explanation also tries to say The voltage is undetermined when both the indicator and the disk are rotated regardless of whether the magnet is moving There is an EMF and a nonuniform charge density but no reaction of the indicator An electric field is generated but no voltage is brought out for display This differs from the different relative motions of the parts of a rectilinear homopolar generator where the answer would be No I think this is explanation is unnecessarily complex Simply stated  If the magnet rotates or not doesnt make any difference If both indicator and disk rotate only the relative difference in rotation is relevant for the voltage seen on the indicator which means if both rotate at the same speed the indicator doesnt see any voltage The reason for this is simple if both rotate at the same speed then also the wires of the indicator circuit will develop the same voltage as the disk itself the wire behaves the same as a second disk therefore the indicator wouldnt see any voltage difference Peace