PURPOSE: To demonstrate levitation of a magnet above a high-temperature superconductor.

DESCRIPTION: A one-inch diameter superconducting disc is set on a conducting base in a bath of liquid nitrogen. A cubic samarium cobalt magnet levitates above the superconductor. Note that to show the Meissner effect you must place the magnet on the disc before cooling it down. When the superconductor passes through its transition temperature the magnet rises up by itself and levitates.

SUGGESTIONS: TV is available on request for large groups.

REFERENCES: (PIRA 5G50.50) See Demonstration Reference File for several papers on high-temperature superconductivity and the Meissner effect.

EQUIPMENT: One-inch superconducting disc on conducting base in styrofoam container of liquid nitrogen, 0.2" cube samarium cobalt magnet, tweezers.

SETUP TIME: 5 min.

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