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Last Updated: Thursday, 10 April, 2003, 07:19 GMT 08:19 UK
Scientists levitate gold coins
Scientists have shown that levitation is not just a trick from a Harry Potter book.

Levitating coins
The coins "float" on cold oxygen
Researchers at the University of Nottingham have used magnetism to make solid objects such as coins float in the air.

Scientists have already proven strong, varying magnetic fields could exert an upward force on objects in their path.

The Nottingham team found this effect could be dramatically enhanced in cold oxygen.

Magnetic levitation occurs when the magnetic force is strong enough to overcome gravity and balance a body's weight.

Cold oxygen provides extra buoyancy through the "magneto-Archimedes" effect - literally allowing an object to float in the air.

No conjuring trick

Laurence Eaves and colleagues at the University of Nottingham's School of Physics and Astronomy used the technique to levitate a gold coin, a 1 coin, two kinds of crystal and a piece of lead.

They wrote in the journal Nature: "In magnetic levitation, a strong and spatially varying magnetic field exerts an upward force on a body that is sufficient to counteract its weight due to gravity.

"Here we show that this effect can be enhanced by immersing the body in cold oxygen gas, which provides a further strong and adjustable buoyancy force that allows a wide range of materials to be levitated in an open, unpressurised vessel."

The objects could be moved simply by adjusting the strength of the magnetic field. But the experiment is more than a conjuring trick.

According to the scientists, the technique could be adapted for use in separating minerals.

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