Ernst Chladni

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Ernest Florenz Friedrich Chladni (November 30, 1756–April 3, 1827) was a German physicist.

Chladni was born in Wittenberg. His important works include research on vibrating plates and the calculation of the speed of sound for different gases.

Contents 1 Chladni Plates 2 Other Works 3 See also 4 Further reading 5 External links

[edit] Chladni Plates

One of Chladni's most well known achievements was inventing a technique to show the various modes of vibration in a mechanical surface.

Chladni's technique, first published in 1787 his book, Entdeckungen über die Theorie des Klanges, consists of drawing a bow over a piece of metal whose surface is lightly covered with sand. The plate is bowed until it reaches resonance and the sand forms a pattern showing the nodal regions . Since the 20th century it has become more common to place a loudspeaker driven by an electronic signal generator over or under the plate to achieve a more accurate adjustable frequency.

Variations of this technique are commonly used in the design and construction of acoustic instruments such as violins, guitars, and cellos.

[edit] Other Works

He invented a musical instrument called Chladni's euphonium, consisting of glass rods of different pitches, which should not be confused with a brass euphonium. He also discovered Chladni's law.

In 1794, Chladni published, in German, Über den Ursprung der von Pallas gefundenen und anderer ihr ähnlicher Eisenmassen und über einige damit in Verbindung stehende Naturerscheinungen, (On the Origin of the Pallas Iron and Others Similar to it, and on Some Associated Natural Phenomena), in which he proposed that meteorites have their origins in outer space. This was a very controversial statement at the time, and with this book Chladni also became one of the founders of modern meteorite research.

[edit] See also

Based on Chladni's work, photographer Alexander Lauterwasser captures imagery of water surfaces set into motion by sound sources ranging from pure sine waves to music by Ludwig van Beethoven, Karlheinz Stockhausen and even overtone singing.

[edit] Further reading

• Rossing T.D. (1982) Chladni's Law for Vibrating Plates, American Journal of Physics 50, 271-274
• Marvin U.B. (1996) Ernst Florenz Friedrich Chladni (1756-1827) and the origins of modern meteorite research, Meteoritics & Planetary Science 31, 545-588

[edit] External links

• Examples with round, square, stadium plates and violin shapes
• Chladni plates
• Chladni Plate Mathematics by Paul Bourke
• Electromagnetically driven Chladni plate
• Use of Chladni patterns in the construction of violins
• Chladni patterns for guitar plates