The electric flour voltage test

Granular materials give off a zap just before slipping

By Rachel Ehrenberg, 15:18 PM June 8, 2012

Ordinary baking flour isn’t the most electrifying substance, but spilling a box of the stuff yields a jolt of voltage that has scientists excited about their prospects for sensing catastrophic events like earthquakes and industrial accidents.

Scientists have known for years that materials including rock, crystals and adhesives like ordinary office tape can produce an electrical signal as they fracture or crack under a load. It’s also known that before a granular material can flow, the space...

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