Is it only metals that respond to magnetic forces?

A fridge magnet can affect more than just metal. 

17th December 2009
Is it only metals that respond to magnetic forces? (iStock)

Asked by: Chris Ormsby, Taunton

Armed with a small magnet and some objects, it’s easy to get the impression that only certain varieties of metal, such as steel, respond to magnetic fields. In fact, every material – wood, plastic, even water – will respond to a magnetic field, if it’s strong enough. That’s because every material possesses a property known as diamagnetism, by which the electrons within the material repel magnetic fields.

Given a sufficiently powerful magnet, this diamagnetic repulsion can produce spectacular effects. In 1997, a team at the University of Nijmegen in the Netherlands used the effect to levitate a frog, using a magnetic field over a million times more powerful than that of the Earth.


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