Graphite – pyrolytic graphite, the same carbon as pencil lead – floats above neodymium magnets at room temperature with no power, because of diamagnetism: a magnetic field shifts the orbital motion of the electrons in every material so that it pushes back. In iron that push is buried under a far stronger pull; graphite, whose electrons circulate freely within its carbon sheets, is one of the most strongly diamagnetic materials at room temperature, so a thin, well-stacked chip is pushed up harder than gravity pulls it down, and magnets with alternating poles hold it in a magnetic bowl (Simon & Geim, J. Appl. Phys. 2000). Thin pencil leads float over fine magnet arrays too, and water is repelled far more weakly – which is why a live frog took a 16-tesla magnet at the High Field Magnet Laboratory in Nijmegen (Berry & Geim 1997; the 2000 Ig Nobel Prize, a decade before Andre Geim’s Nobel for graphene).
Your turn: Your body is mostly water, so what would it take to float you? Answer in the comments.
SOURCES
– Simon & Geim 2000, Diamagnetic levitation: Flying frogs and floating magnets, J. Appl. Phys. 87:6200, doi:10.1063/1.373483:
– Berry & Geim 1997, Of flying frogs and levitrons, Eur. J. Phys. 18:307 (High Field Magnet Laboratory, Nijmegen):
– French, The Wonders of Levitation (University of Bristol), arXiv:1010.5761:
Video: “Diamagnetic Pyrolytic carbon levitating over permanent magnets” (Peter L., CC BY 3.0), via Wikimedia Commons. Photos via Wikimedia Commons: “Diamagnetism levitation simple experiment” (MysteriousLion, CC BY-SA 4.0); “Frog diamagnetic levitation” (Lijnis Nelemans, CC BY-SA 3.0); “Mechanical pencil lead” (Bob Ionescu, free use with attribution); “Rubber horse surfing pyrolytic carbon” (yellowcloud, CC BY 2.0, thumbnail). Animations: original. Full sources in the description.
Narration is AI-generated (ElevenLabs). The floating-chip clips are Peter L.’s footage of a pyrolytic graphite chip levitating over neodymium magnets, at normal speed; nothing is holding it up. The floating pencil lead is a separate experiment photographed by MysteriousLion; the frog is the levitating frog of the High Field Magnet Laboratory in Nijmegen (photo: Lijnis Nelemans). The atom, iron, graphite-sheet and magnetic-bowl animations are original and schematic, not to scale (the electron orbit is the classical picture); the water-vs-graphite gauge is to scale, from Simon & Geim’s table of susceptibilities. Facts are from Simon & Geim 2000 (J. Appl. Phys.), Berry & Geim 1997 (Eur. J. Phys.), French (University of Bristol), T.-C. Chiang (University of Illinois), Iida et al. 2015 and Improbable Research. Because two photos are ShareAlike-licensed, THIS VIDEO is also released under CC BY-SA 4.0: you may share and adapt it, including commercially, as long as you credit the original creators (see above) and license your own version CC BY-SA 4.0 too. License:
Full breakdown on the channel.
#Shorts #Graphite #Diamagnetism #Levitation #Magnets #Physics
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