What does diamagnetism mean?
Diamagnetism is the weakest form of magnetism shown by materials: when placed in a magnetic field, a diamagnetic substance develops a magnetization directed opposite to the field, so it is feebly repelled rather than attracted. The effect arises because an applied field induces tiny circulating currents in the atoms, which oppose the change producing them. All matter exhibits some degree of diamagnetism, but it is usually masked by stronger effects; it becomes observable only in substances such as bismuth, copper, graphite, and water, where no other magnetic behavior dominates. In everyday terms, diamagnetism explains curious demonstrations such as levitating frogs or floating graphite over magnets, and in physics it underpins the Meissner effect, by which superconductors expel magnetic fields entirely. The word belongs to formal scientific registers and is essential vocabulary for anyone studying electromagnetism or condensed-matter physics.
nounThe property of certain materials that are weakly repelled by a magnetic field and acquire a magnetization opposite in direction to the applied field; the phenomenon exhibited by substances whose atoms have no net magnetic moment, such as bismuth, copper, and water.
- The weak repulsion of a material by a magnetic field, arising from induced currents that oppose the applied field (physics).
"Bismuth is prized in physics demonstrations because its strong diamagnetism allows it to levitate above powerful magnets."
"Water's faint diamagnetism is normally imperceptible, but under an extremely strong field it can make small objects float."
"Superconductors display perfect diamagnetism, expelling magnetic fields entirely — a phenomenon known as the Meissner effect."
Diamagnetism is why a live frog once floated in mid-air inside a powerful magnet — every substance, even you, is very slightly repelled by magnetic fields.
Reviewed by Deb Chak, Editor. AI-assisted content curated by RJS Tech Solutions LLP.
Etymology of diamagnetism
The term combines the Greek-derived prefix dia- (meaning 'through, across, or apart') with 'magnetism', which traces back through Latin magnes to Greek magnētis lithos, 'stone of Magnesia', referring to the lodestone. The adjective 'diamagnetic' was coined in the nineteenth century as scientists, most notably Michael Faraday, classified materials by their response to magnetic fields; the noun 'diamagnetism' followed as the name for this distinct class of behavior. Related English derivatives include paramagnetism, antiferromagnetism, and the everyday word 'magnet' itself, all descending from the same Greek root.
Related word forms
How diamagnetism is actually used
A technical term used chiefly in physics, chemistry, and materials science; rare in everyday speech. It names both the property of individual substances and the broader class of magnetic behavior contrasted with paramagnetism and ferromagnetism.
Easily confused with diamagnetism
In paramagnetism materials are weakly attracted to a magnetic field and align with it, whereas diamagnetism involves weak repulsion and magnetization opposing the field.
Ferromagnetism is the strong, permanent magnetism of iron and its like, vastly more powerful than the feeble, induced repulsion characteristic of diamagnetism.