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Diamagnetism

 In the end of 1980 several discoveries were made in the  field of superconductivity physics.  Some ceramics were discovered to have superconductive properties at  liquid nitrogen temperatures (-196 deg C).  This led to some wild speculations that it maybe was possible to get superconductivity at room temperature. It could have  great impact on the distribution of electricity. However still today, due to engineering problems, very few applications  has been made of high temperature superconductors.  One very popular experiment is often performed, even at lower grade physics education, to make simple superconductors. One way to detect the superconductivity is that the material has diamagnetic properties.  A  standard magnet can be made hovering on top of a superconductor cooled to liquid nitrogen temperature. In fact a superconductor has "perfect" diamagnetic properties and is often refered as the Meissner effect.   Many  materials have this diamagnetic properties even if they are not a superconductor but the magnetic force is very week.  Pyrolytic graphite is a material wich have enough diamagnetic properties so it can exceed the force of gravity in the magnetic field from a strong neodym magnet.


A lead from a mechanical lead pen , Haber Castell 0.35mm is  hovering  appr 0.5mm on top of 9 neodym magnets,  8x5x3mm, purchased from elfa. Not all leads works well due to differences in manufacturing.