Rabu, 29 April 2009

Floating water bridge

“Water undoubtedly is the most important chemical substance in the world,” explained Elmar Fuchs and colleagues from the Graz University of Technology in Austria in a recent study. “The interaction of water with electric fields has been intensely explored over the last years. We report another unusual effect of liquid water exposed to a dc electric field: the floating water bridge.”

When exposed to a high-voltage electric field, water in two beakers climbs out of the beakers and crosses empty space to meet, forming the water bridge. The liquid bridge, hovering in space, appears to the human eye to defy gravity.

Upon investigating the phenomenon, the scientists found that water was being transported from one beaker to another, usually from the anode beaker to the cathode beaker. The cylindrical water bridge, with a diameter of 1-3 mm, could remain intact when the beakers were pulled apart at a distance of up to 25 mm.



Why water would act this way was a surprise, Fuchs told PhysOrg.com. But the group’s analyses have shown that the explanation may lie within the nature of the water’s structure. Initially, the bridge forms due to electrostatic charges on the surface of the water. The electric field then concentrates inside the water, arranging the water molecules to form a highly ordered microstructure. This microstructure remains stable, keeping the bridge intact.

The scientists reached the microstructure hypothesis after observing that the density of the water changes between the beaker edges and the center of the bridge. A microstructure consisting of an arrangement of water molecules could have a similar density variation.

Source: Physorg