I7-21. Superconductivity - Magnet Levitation

Purpose

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

Equipment

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

Suggestions

TV is available on request for large groups.

Setup Time

5 minutes.

Images

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.

References

E. Bochenek, R. Fischer, and H. Voigt, Conception and Operation of a Meissner-Ochsenfeld Effect Motor with High Tc Superconductors, Journal of Less-Common Metals, 151, 473-480 (1989). P. J. Ouseph, Meissner oscillator, AJP 57, 955-956 (1989). Raymond E. Benenson, Demonstration of Magnetic Images, TPT 29, 54-55 (1991). E. Guarner and A. M. Sanchez, The Superconducting Bird: A Didactical Toy, TPT 30, 176-179 (1992).