Diamagnetic Graphite - Physics Demonstrations - Diamagnetic Graphite | Physics Undergraduate Labs

The Halbach array generates powerful localized magnetic fields (>1 Tesla near surface). Keep electronic devices, credit cards, and magnetic storage media at least 30 cm away. Individuals with pacemakers or other implanted medical devices should maintain distance >1 meter. Neodymium magnets can pinch skin severely if they snap together—handle the array carefully and never attempt to disassemble.

Purpose

Thin pyrolytic graphite sheets levitate above a Halbach magnet array, demonstrating diamagnetic repulsion regardless of pole orientation. Students see that all materials respond to magnetic fields, not just ferromagnets, and observe stable levitation arising from negative magnetic susceptibility.

Dark gray rectangular graphite sheet on a 3x4 array of gold and silver cubic magnets on a green surface

Four dark gray graphite pieces of varying thickness in front of the Halbach array, with one small piece sitting on top of the magnets

Figure 1: A pyrolytic graphite sheet on the 3×4 Halbach magnet array. The thinner sheets visibly levitate above the magnets; video projection is needed for the audience to see the gap.

Figure 2: Graphite sheets in thicknesses from 0.3 mm to 3.4 mm (all 34.5 × 19 mm rectangles except the thinnest, which is ~16 mm square). Thinner pieces levitate more dramatically.

Box of Graphite

1
Pink Note Card

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3 × 4 Magnet Array

1

Safety Warnings

Warning: Strong Magnetic Field

Purpose