Light Powers Levitating Magnets

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Magnetic levitation is old hat these days, with maglev

trains operating

in China and planned systems taking shape in other countries. But they run

by manipulating the train, which is "floating" on a magnetic field, with electricity. Now a team of researchers in Japan have found a way to manipulate magnetically levitating objects using light. The technique could lead to new forms of powered maglev transportation systems and could make solar-powered

generators more efficient.

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To make the levitating graphite device, Masayuki Kobayashi and professor Jiro Abe of Aoyama Gakuin

University in Kanagawa arranged a set of magnets made of neodymium, iron and boron

in a grid. They then put a piece of graphite on top of the grid. When exposed to an

external magnetic field, graphite — specifically an artificial type called

pyrolitic graphite — generates its own field that repels the external one, a

property called diamagnetism. That makes graphite levitate when it's placed on

top of permanent magnets.

The researchers then hit the graphite with a laser. The

laser heated up part of the graphite and changed its susceptibility to the

surrounding magnetic field. Hitting the graphite in the center made it sink, as

the heating was more even. Aiming

the laser at the edge made it move in the direction of the beam.

Gotta-See Video: Magnetic Floating Centerpiece

Next, they put the graphite on top of a tower of

cylindrical magnets and hit the edge of it with the laser beam. The result

was a little graphite disc spinning at up to 200 rpm when it was exposed to the

laser — or sunlight.

The researchers published the results of their study in the Journal of the

American Chemical Society.

Being able to generate useful mechanical motion this way could

change the way solar power setups are made. A spinning disk could run a

generator directly rather than extracting the energy in several steps such as

converting the DC current from a photovoltaic cell or using solar power to make

steam.

Via Physorg,

Journal of the American

Chemical Society

Credit: Masayuki Kobayashi and Jiro Abe

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