Diamagnetic levitation - magnet vs wood, ice, and graphite скачать в хорошем качестве

Diamagnetic levitation - magnet vs wood, ice, and graphite

I demonstrate diamagnetic levitation. Earlier, I show that wood, ice, and pencil leads are repelled by magnets. These materials are diamagnetic. Additional information. 1) I have verified that Pentel 0.5mm and 0.9mm pencil leads have good diamagnetic properties. Thick pencil leads may contain iron and will be attracted to magnets. For levitation, I use neodymium magnets in the shape of 1x1x1 cm cubes. Neodymium magnets are made of a combination of neodymium, iron, and boron. These magnets produce a strong magnetic field but are quite fragile. Due to the strong magnetic field, special care must be taken in experiments with neodymium magnets. 2) Diamagnetism was discovered by the Dutch physicist Anton Brugmans in 1778. Anton Brugmans studied the behavior of bismuth in a magnetic field. Subsequently, this phenomenon was further explored by Michael Faraday, who also named it diamagnetism. The classical theory of diamagnetism was presented in 1905 by the French physicist Paul Langevin. 3) In classical physics, diamagnetism is explained by the effect of the Lorentz force on electrons orbiting atomic nuclei. Depending on the direction of rotation of the electron, the Lorentz force slows down or accelerates the electrons, which generates the magnetic moment of the atom and, consequently, the diamagnet is pushed out of the non-uniform magnetic field. It can also be explained in another way. By bringing the magnet closer to the diamagnet an electric field is created (by magnetic induction) that changes the angular momentum of the orbiting electrons, which generates a magnetic moment. The discussion with the calculation is available, e.g., in Feynman's lectures https://www.feynmanlectures.caltech.e... It boils down to Lenz's law, which says that a material resists a change of the magnetic field. 4) The Bohr–Van Leeuwen theorem https://en.wikipedia.org/wiki/Bohr%E2... says that the magnetism of a substance is essentially a quantum phenomenon, and therefore a full understanding of diamagnetism is possible within the framework of quantum mechanics. You can read more about it, e.g., in Feynman's lectures https://www.feynmanlectures.caltech.e...