If Copper Isn't Magnetic, Why Does a Magnet Float Inside Copper? — The History of Neodymium

Subscribe to ⁨‪@VEIN.Materials‬ ⏱️ If this documentary was worth your time, consider buying me a coffee. Every coffee goes directly toward researching, writing, and producing the next story, so I can keep making documentaries like this. Thanks for watching, and for supporting independent storytelling. https://buymeacoffee.com/VEIN.Material This video explains why a neodymium magnet falls slowly through a copper pipe even though copper isn't magnetic at all, tracing the science of eddy currents and the two-century history behind their discovery. It starts with a simple kitchen experiment—dropping a magnet down a copper pipe versus a plastic one—and rules out air resistance, friction, and diamagnetism as explanations before revealing the real cause: electromagnetic induction and eddy currents. From there it journeys back to 1824 Paris, where François Arago first noticed copper dragging on a swinging compass needle, through the failed theories of Siméon Denis Poisson, the London experiments of Charles Babbage and John Herschel, the self-taught genius William Sturgeon, and finally Michael Faraday's 1831 breakthrough explanation, Heinrich Lenz's law, and the twentieth-century race to build the powerful neodymium magnets that make the effect visible today. What's covered in this video: A copper pipe and neodymium magnet experiment shows the magnet sinking slowly compared to a normal free-fall drop. Air resistance, friction, and copper's weak diamagnetism are each tested and ruled out as the cause of the slow fall. A saw cut down the length of the pipe nearly kills the effect, revealing that circulating eddy currents, not the metal itself, are responsible. François Arago's 1824 experiments in Paris with a swinging compass needle and rings of copper first reveal "magnetism of rotation." Siméon Denis Poisson proposes an incorrect theory of lingering induced magnetism that briefly satisfies the scientific community. Charles Babbage and John Herschel in London test spinning copper discs, rank metals by conductivity, and slice discs into slits that weaken the drag. William Sturgeon, a self-taught former soldier who invented the practical electromagnet, gets close to the correct electrical explanation but runs out of time. Michael Faraday's 1831 experiments with iron rings, sliding coils, and a spinning copper disc finally prove that changing magnetism creates electric current. Heinrich Lenz's 1834 law explains why the falling magnet settles into a constant speed instead of speeding up or stopping. Léon Foucault demonstrates that the energy of the effect turns into heat, giving eddy currents their French name, Foucault currents. The twentieth-century development of stronger magnets, from alnico to ferrite to samarium-cobalt, explains why weak old magnets could never show this effect clearly. Masato Sagawa's work at Sumitomo Special Metals around 1982 leads to the invention of neodymium magnets strong enough to make the eddy current brake dramatically visible. ▶️ Watch Next: Is This the Most Extreme Metal Inside the Blackbird and a Nuclear Reactor? — The History of Inconel    • Is This the Most Extreme Metal Inside the ...   Is Helium the Only Element That Refuses to Freeze? — The History of Helium    • Is Helium the Only Element That Refuses to...   Why Did the H-Bomb Almost Fail Over One Impossible Element? — The History of Tritium    • Why Did the H-Bomb Almost Fail Over One Im...   Mentioned in this video: neodymium magnet, copper pipe, eddy currents, diamagnetism, François Arago, Henri-Prosper Gambey, Alexander von Humboldt, Siméon Denis Poisson, Joseph Louis Gay-Lussac, Charles Babbage, John Herschel, Thomas Seebeck, Pierre Prévost, Jean-Daniel Colladon, Leopoldo Nobili, André-Marie Ampère, William Sturgeon, Royal Society, Michael Faraday, Hans Christian Ørsted, Heinrich Lenz, Léon Foucault, Foucault currents, Kotaro Honda, Tokushichi Mishima, alnico, ferrite magnets, Karl Strnat, samarium-cobalt, Zaire (Democratic Republic of the Congo), Masato Sagawa, Fujitsu, Sumitomo Special Metals, electromagnetic induction