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.