Electromagnetic levitation of a conducting cylinder

A long conducting nonmagnetic circular cylinder may be supported on the magnetic field produced by an alternating current carried in two horizontal wires parallel to the axis of the cylinder. The cylinder will float stably provided it is not too high and not displaced too far from the centre of symmetry. The boundaries of the region of stable floating have been determined for a 2cm-diameter aluminium bar when the wires are 2, 4 and 6cm apart, and when the frequency of the supply is 50, 400 and 2000c/s. The power loss in the bar has also been calculated. Both the width of the region of stable floating and the loss in the bar increase as the distance between the wires increases and as the frequency is raised. The current required to lift the bar decreases as the frequency is raised and as the wires are brought closer together. The theoretical results have been checked by experiment for one configuration.