My textbook says that Diamagnetic substances align their longest axis perpendicular to the field in uniform magnetic field while paramagnetic substances align their longest axis parallel to the field.

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The paramagnetic case makes sense because the torque on the material would be zero when it is inclined along the magnetic field.

But why is it not in the case of diamagnetic materials?

  • $\begingroup$ What are the axes? Are we discussing small samples (e.g. nanoparticles)? $\endgroup$
    – Mauricio
    Apr 1, 2022 at 12:48
  • $\begingroup$ @Mauricio what I understood from the text is that direction in which magnetic intensity is more or less according to the substance's ( paramagnetic or diamagnetic) orientation in external applied field . My question is why in case of diamagnetic substance ( let gold rod )it should be perpendicular to the field ? $\endgroup$
    – user306932
    Apr 1, 2022 at 14:42
  • $\begingroup$ @Mauricio can I say that if we considered a small loops likes eddies in diamagnetic substance , the magnetic moment will be zero , as the current flowing in this loop will be perpendicular to the area vetor of that loop and hence magnetic moment is zero which implies torque is zero ? $\endgroup$
    – user306932
    Apr 1, 2022 at 14:46
  • 1
    $\begingroup$ From what I have found (not much) it has to do with reducing/increasing the magnetisation inside the material. $\endgroup$
    – Mauricio
    Apr 1, 2022 at 17:38
  • $\begingroup$ Possible duplicate: physics.stackexchange.com/questions/410612/… $\endgroup$
    – Mauricio
    Apr 1, 2022 at 17:39


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