I mean, what would happen if we spread out some good amount of copper filings on a paper and place a kind of hypothetical device which produces a magnetic field which changes at some regular intervals? Will the copper filing particles react by showing some kind of movement? Why I think so? I think so because the changing magnetic field will produce some induced current in the particles and thereby they will produce their own magnetic fields. Therefore, they must show some kind of movements. Please keep in mind that I am just a 10th grader student. So, explaining in simple words will prove to be worthy for me.


1 Answer 1


As far as I remember, copper is diamagnetic, so copper filings will tend to move even in constant magnetic field.

EDIT (8/23/2019): Another thing: the changing magnetic field will indeed create changing electric field, which will create current in the copper filings, and the magnetic field will act on the current, producing motion.

  • $\begingroup$ Ya, it's all right... But what will happen in the aforementioned condition? How will it react to it? Please elaborate. $\endgroup$ Aug 23, 2019 at 6:18
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    $\begingroup$ Diamagnetism tends to be a very, very weak effect. All materials essentially have a diamagnetic component, but in many materials it's masked by the presence of other, stronger forms of magnetism such as paramagnetism or ferromagnetism or antiferromagnetism. It's only when none of these other, stronger forms of magnetism are present in a material that the material becomes diamagnetic by default. I think that it would be very difficult to see any movement of copper filings using any magnet that one is likely to find in a typical home. $\endgroup$
    – user93237
    Aug 23, 2019 at 7:09
  • $\begingroup$ The induced currents are the real issue. It likely depends a fair bit on the field change and the shape of the filings since the force will depend on the difference in induced current between nearby filings - I suspect one needs a steep gradient in the field to get motion. $\endgroup$ Aug 23, 2019 at 9:33

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