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Volta's Hailstorm
England, second half 19th century
This Hailstorm would be set upon a table, or other grounded object. Wood conducts static electricity, and so does pith - or rather, the moisture within the wood and pith conducts. When the brass ball is connected to an electrostatic generator, and electrified, the electric field induces an opposite charge in the pith balls. They are pulled up to the top, where they take on charge and are pushed back down. They leap up and down, as the induced charge reverses, like a hailstorm or like popcorn in a popper. Look closely at the pith balls. They're smooth and shiny. As the balls leap up and down, they hit the top and bottom of the Hailstorm. Over time, this flattens down the surface until it is very smooth. The same effect as the Hailstorm is used today in electrostatic precipitators, pollution-control equipment that removes fine particles from smokestack gases. Instead of bouncing back and forth, however, the particles are trapped in special electrodes. |
| The Bakken A Library and Museum of Electricity in Life 3537 Zenith Avenue South Minneapolis, MN 55416-4623, USA Join our E-Mail List Contact Us Tele: 612-926-3878 Fax: 612-927-7265 |
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Volta's Hailstorm is one of the classic demonstrations,
and this is as pure a "hailstorm" as you can find. It's about
four inches high.