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17 April 2014 12:48 pm ,
Vol. 344 ,
Officials last week revealed that the U.S. contribution to ITER could cost $3.9 billion by 2034—roughly four times the...
An experimental hepatitis B drug that looked safe in animal trials tragically killed five of 15 patients in 1993. Now,...
Using the two high-quality genomes that exist for Neandertals and Denisovans, researchers find clues to gene activity...
A new report from the Intergovernmental Panel on Climate Change (IPCC) concludes that humanity has done little to slow...
Astronomers have discovered an Earth-sized planet in the habitable zone of a red dwarf—a star cooler than the sun—500...
Three years ago, Jennifer Francis of Rutgers University proposed that a warming Arctic was altering the behavior of the...
- 17 April 2014 12:48 pm , Vol. 344 , #6181
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ScienceShot: Why a Water Bridge Doesn't Collapse
23 September 2013 3:15 pm
If you apply an electric voltage across two water-filled beakers and separate them, something strange happens: The water stretches from beaker to beaker, creating a bridge that defies gravity. Water bridges were discovered 120 years ago, but no one has ever been sure why they do not collapse. One theory is that the voltage makes the water molecules line up, creating a “dielectric” tension that stops the bridge from falling. Another argues that surface tension—the tendency of a water’s surface to shrink inwards—keeps the bridge aloft. Now, researchers believe that water bridges rely on both strategies. Reza Namin at the Sharif University of Technology in Tehran and colleagues measured various parameters across the length of a water bridge, including voltage, current, and bridge diameter. Then they plugged the data into a computer simulation to calculate the forces involved. The results, to be published next month in Physical Review E, reveal that dielectric tension and surface tension each carry about half a water bridge’s weight. The results, the researchers believe, could help engineers develop electrowetting, a method of using electricity to adjust the adhesion of fluids to a screen that is expected to be used in the next generation of e-book readers.