Levitator: Aluminum dish floats four inches off platform.

5K20.41 • D+15+24

Levitator: Aluminum dish floats four inches off platform. This apparatus is a magnetic levitator, illustrating Lenz's law. The levitator can support an aluminum bowl about a foot in mid air in stable equilibrium. The levitator is an electromagnet of special design. The top consists of concentric wire coils and an hexagonal array of iron cores. 220 V.A.C., at 60 Hertz, is applied to the coils, causing an intense alternating magnetic field. When the aluminum pan is placed in the field, eddy currents form in the aluminum, causing magnetic fields in the direction opposite to the levitator fields. The force on the bowl is upward, and sufficient to counteract the weight of the aluminum. Should the bowl move to one side, the eddy currents give rise to a greater repulsive force on that side, causing the bowl to move back to center position. If the bowl tips, it experiences a force that restores it to horizontal equilibrium. If a wood stick is used to press down on the bowl, the eddy currents increase significantly, causing the bowl to heat up dramatically. Because the coil windings of the levitator have a large inductive reactance, a large capacitance is inserted in the ac circuit (in the bottom part of levitator cabinet) to raise the power factor close to unity. I.E.: The current in the levitator coils is kept at a maximum, and the current supplied by the source is at a minimum.