Equipment: A high Tc YBaCuO superconductor with a piece of yellow tape affixed to the top surface for visibility purposes, a small NdBFe magnet, a petri dish, a foam support, a pair of plastic forceps, a small wire hoop, a foam cup, a small (~2L) dewar of liquid nitrogen, a video camera, safety goggles and safety gloves.

What it does: The NdBFe magnet levitates above the high Tc superconductor when it is superconducting.

Concepts Demonstrated: Superconductivity.

Classroom assembly:

1. Place the petri dish on the foam support.
2. Place the superconductor in the petri dish.
3. Center the NdBFe manget on the superconductor using the forceps.
4. Pour liquid nitrogen into the petri dish until the superconductor is fully submerged. WEAR APPROPRIATE SAFETY GEAR.
5. Continue to add liquid nitrogen as it boils off. When the superconductor reaches critical temperature (~90K), it will superconduct and the magnet will levitate. Be patient; this can take a while.
6. Spin the magnet with the forceps.
7. Pass the wire hoop around the magnet to show it is levitating.
8. Gently push the magnet with the forceps to demonstrate its range of stability over the superconductor.

Cautions:

• Liquid nitrogen can cause severe burns and blindness. Use with caution.
• The magnet is strong. Handle with care.
• The superconductor is brittle. Handle with care.

Setup Time: Medium.

Difficulty: Straightforward.

Visibility: The video camera is essential in all settings. With the video camera, this demonstration is appropriate for large lecture halls.

Related demonstrations: The wire coil in liquid nitrogen demonstration is a nice lead in to this demonstration.

References: PIRA 5G50.50

Original Construction: Purchased