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Why are diamagnetic materials weakly repelled by magnets?

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Diagram showing a circular loop of wire with an electric current, surrounded by curved blue lines representing magnetic field lines that loop around the wire and pass through its center. — magnetism Some lines of the magnetic field B (blue) for an electric current I (gold) in a loop.

Diamagnetic materials are weakly repelled by magnets because of how their electrons respond to an external magnetic field. When placed in such a field, the orbital motion of the electrons within the material's atoms is altered, causing the atoms to generate their own induced magnetic field.12

In accordance with Lenz’s law, this induced magnetic field is directed in opposition to the applied external field. Because the induced field opposes the external one, the material experiences a force that pushes it toward regions of decreasing field strength, resulting in a weak repulsion. This property is characterized by a negative magnetic susceptibility, meaning the material's magnetization is always directed against the applied field. While all substances exhibit this diamagnetic effect, it is often masked in materials that also possess stronger magnetic properties, such as paramagnetism or ferromagnetism.3241