Superconductivity Experiment Kit

Three experiments, one kit

1. Critical temperature (T_c) by four-point resistance. A YBCO bar with four contacts is wired to the measurement unit, which drives a constant current through the outer contacts and records the voltage across the inner pair while a thermometer on the sample tracks its temperature. As the sample warms from 77 K the resistance rises from zero to the normal-state value in a sharp step near 92 K: the resistive transition that Heike Kamerlingh Onnes first saw in mercury in 1911. The data stream to a laptop over USB and plot live; students fit the normal-state slope and read T_c from the knee of the curve.

2. Levitation force. With the magnet array on a force sensor, the levitator is brought towards the magnets and pulled away in a smooth motion. On the way in the force rises to about 1 N of repulsion (Meissner effect plus pinning); on the way out it passes through zero and becomes attractive. The difference between the two curves is hysteresis, the signature of flux pinning, and it is measured with macroscopic, quantitative tools.

3. Meissner effect and flux pinning demonstrations. The same levitator and magnet array give the classic demonstrations: repulsion regardless of magnet polarity, locking in place, hanging upside down and holding an angle, and guided motion.

What is in the box

• Measurement unit: constant-current source, voltage and temperature inputs, USB data logger with plotting software
• YBCO sample bar for the four-point measurement, with contacts and thermometer
• Round Quantum Levitator (Medium standard 4.5×0.8 cm or Enhanced 4.5×1.5 cm, depending on the variation)
• Handheld magnetic device (magnet array) and plastic tweezers
• Printed instructions; the full teacher’s guide is online

Not included: liquid nitrogen (about one litre per session; see the liquid nitrogen guide), a laptop, and a force sensor for experiment 2 (any standard school force sensor with a stand will do).

Who it is for

Advanced high-school physics, IB and A-level practical work, undergraduate teaching labs and science-fair projects that need real measured data rather than a demonstration. The four-point method, the resistive transition and the force hysteresis each map directly onto curriculum topics in resistance, phase transitions and magnetism.