Physicists Measure Elusive 'Persistent Current' That Flows Forever

Image: Harris made the first definitive measurement of an electric current that flows continuously in tiny, but ordinary, metal rings. (Credit: Jack Harris/Yale University)

From Science Daily:

Science Daily (Oct. 12, 2009) — Physicists at Yale University have made the first definitive measurements of “persistent current,” a small but perpetual electric current that flows naturally through tiny rings of metal wire even without an external power source.

The team used nanoscale cantilevers, an entirely novel approach, to indirectly measure the current through changes in the magnetic force it produces as it flows through the ring. “They’re essentially little floppy diving boards with the rings sitting on top,” said team leader Jack Harris, associate professor of physics and applied physics at Yale. The findings appear in the October 9 issue of Science.

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