We describe and discuss an experimental set-up which allows undergraduate and graduate students to view and study magnetic levitation on a type-I superconductor. The demonstration can be repeated many times using one readily available 25 liter liquid helium dewar. We study the equilibrium position of a magnet that levitates over a lead bowl immersed in a liquid hand-held helium cryostat. We combine the measurement of the position of the magnet with simple analytical calculations. This provides a vivid visualization of magnetic levitation from the balance between pure flux expulsion and gravitation. The experiment contrasts and illustrates the case of magnetic levitation with high temperature type-II superconductors using liquid nitrogen, where levitation results from partial flux expulsion and vortex physics.
Cite
@article{arxiv.1207.5992,
title = {Magnetic levitation on a type-I superconductor as a practical demonstration experiment for students},
author = {M. R. Osorio and D. E. Lahera and H. Suderow},
journal= {arXiv preprint arXiv:1207.5992},
year = {2015}
}