Magnetic levitation on a type-I superconductor as a practical demonstration experiment for students

TL;DR

This paper presents a practical educational experiment demonstrating magnetic levitation on a type-I superconductor, combining simple measurements with analytical calculations to visualize flux expulsion and levitation physics.

Contribution

It introduces a repeatable, accessible demonstration setup for students to study magnetic levitation on type-I superconductors using liquid helium.

Findings

Visualizes magnetic flux expulsion and levitation physics.

Contrasts type-I and type-II superconductor levitation mechanisms.

Provides an educational tool for understanding superconductivity phenomena.

Abstract

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.