Magic: Levitation

The noisy device is the levitator whch can support an aluminum bowl about a foot in mid air in stable equilibrium. This levitation illustrates Lenz's law that the eddy current induced by a changing magnetic field produces a magnetic field of its own which opposes the changing magnetic field and is repelled by it.

The levitator is an electromagnet of special design. The top consists of concentric wire coils with a hexagonal array of iron cores. Electric power at 220 Volts A.C. at 60 Hz frequency is applied to the coils causing an intense alternating (changing) magnetic field. The changing magnetic filed produces and electric field which induces eddy currents in the aluminum pan when it is placed in the changing field.

By Lenz's law the force on the bowl is such to repel it from the electromagnet levitator (the magnetic fields repel each other) and the force is sufficient to overcome the weight of the aluminum. The aluminum bowl then floats.

The changing magnetic field is more intense at the edge than the center and thus induces more current and repulsion if the bowl moves off center. The bowl would have to move higher and gain gravitational potential energy to be there. The rounded shape of the bowl thus helps it slip back toward the center. The bowl levitates and thus stays at the center. It can be set spinning as I did and one can pass a nonconducting material such as the wood stick to show that no wires are attached.