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24 April 2014 11:45 am ,
Vol. 344 ,
The National Institutes of Health is revising its "two strikes" rule, which allowed researchers only one chance to...
By stabilizing the components of retromers, molecular complexes that act like recycling bins in cells, a recently...
Fossil fuels power modern society by generating heat, but much of that heat is wasted. Semiconductor devices called...
Researchers are gaining insights into what made Supertyphoon Haiyan so powerful and devastating through post-storm...
Millions around the world got a first-hand look at what it was like to be in Tacloban while it was pummeled by...
Major climate data sets have underestimated the rate of global warming in the last 15 years owing largely to poor data...
The tsetse fly is best known as the vector for the trypanosome parasites that cause sleeping sickness and a disease in...
- 24 April 2014 11:45 am , Vol. 344 , #6182
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Bouncing Sand That Made Waves
30 November 1998 8:00 pm
Today is the birthday of Ernst Chladni, a German physicist born in 1756 who helped found the science of acoustics. Chladni, who was a lawyer and music lover as well as a scientist, began studying sound waves in 1786 and worked out mathematical formulas to describe how they travel. His most famous experiment demonstrated that when a thin plate of metal covered with fine sand vibrates, the jiggling sand grains collect along so-called nodal lines--regions where the waves do not bend the plate. These patterns are now called Chladni's figures. He also measured the changes in pitch that occur when an organ pipe is filled with gases other than air, thus showing that the frequency of a sound wave varies according to the molecular composition of the gas through which it passes.
[Source: Roy Porter, Ed., The Biographical Dictionary of Scientists (Oxford University Press, ed. 2, 1994).]