The German scientist Ernst Chladni was one of the pioneers of experimental acoustics. His research on different kinds of vibrations served as the basis for the scientific understanding of sound that later emerged in the 19th century. Starting with a metal plate whose surface had been lightly sprinkled with sand, he found that bowing it produced characteristic patterns that could be related to the physical dimensions of the plate. Chladni was even able to produce a formula that successfully predicted the patterns found on vibrating circular plates. Fine metal filings are sprinkled on the wooden plates, which are then vibrated at as many as seven different frequencies to produce a series of patterns. Much of the final shaping of the plates is directed towards ensuring that the patterns on both of them match and are symmetrical.
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Leonardo da Vinci noted the unusual patterns formed by particles in response to vibrations. So did Galileo, who noticed that bits of bristle on the sounding board of an instrument would move in some areas but not in others. But these so-called "Chladni figures" bear the name of the man who conducted the first in-depth investigations of the phenomenon: a German physicist and musician named Ernst Florens Friedrich Chladni.
Chladni was born in Wittenberg in , to a long line of academics. His father was a law professor and dean of law at the University of Wittenberg. Both his mother and his sister died when he was still quite young. Chladni was mostly educated at home by his father, a strict disciplinarian. The boy was often confined to his room to study by day, and discouraged from fostering friendships, but he loved studying the stars and maps, yearned to travel, and began reading about science at age seven.
As a teenager he was sent to boarding school near Leipzig, rooming with one of his teachers rather than with the other students. His father nixed his desire to study medicine and insisted he earn a law degree instead. Chladni went on to earn degrees in law and philosophy from the University of Leipzig, but his father died just as he completed his studies, leaving Chladni to provide for his stepmother.
But it also freed him to finally pursue his scientific interests. He eked out a nomadic living giving lectures, initially on law, but eventually on geometry, geography, and the field to which he would go on to contribute so much as a researcher: acoustics. Chladni first began conducting experiments in his flat, moving beyond the usual studies of vibrations in string and wind instruments to focus on transverse vibrations of rods — inspired by earlier work by Leonhard Euler and Daniel Bernoulli — before turning to vibrations of plates, then largely an unknown field.
Chladni might not have known it at the time — there is no specific mention in his surviving writings — but a century earlier, on July 8, , Robert Hooke sprinkled sand over a solid metal plate, ran a violin bow along the edge to make the plate vibrate, and noted the unique patterns that formed as the sand grains rearranged themselves along the vibrational nodes. Chladni would take that work to the next level with his systematic investigation of the sound patterns of circular, square, and rectangular plates.
By his own account, Chladni found inspiration in the work of Georg Christoph Lichtenberg , who scattered powders over the surface of electrified resin cakes to produce the patterns known today as Lichtenberg figures. Figuring he could do the same thing with sound, Chladni began scattering sand on his rods and plates. Also, he developed a formula that predicted the sand patterns for vibrating circular plates.
As for the underlying mechanism moving the particles, it appeared to be twofold. The sand particles were bouncing on the rapidly vibrating plates, impinging on the surface at the crests and moving towards the nodes. But Chladni also noticed that his bow shed even finer particles as it moved across the plate, and these finer particles migrated toward the antinodes. This is due to a second transport mechanism, acoustic streaming, first observed by Michael Faraday back in It is the opposite of how airflow generates vibrations in a musical instrument; in this case, the vertically vibrating plates produce a lateral fluid flow along its surface.
It is still widely used today. And his research continues to inspire other scientists. Rather than scattering sand on metal plates, they suspended polystyrene microbeads in water, injected the suspension into a microfluidic device, and stretched a membrane of polysilicone across a circular opening at the base to create a drum that vibrated.
Then they recorded the positions of the microbeads with a camera attached to a microscope. When the plate vibrated, the beads arranged themselves at the antinodes, forming inverse Chladni figures — the result of acoustic streaming in the fluid. The ability to form such patterns in a microfluidic device opens the door to using sound waves to organize objects into specific patterns for various technological applications, such as grouping cells into colonies and then using changing frequencies to shift their size and distribution, thereby affecting their development.
Chladni died in April while on a lecture tour in Breslau, having never held a formal academic position. He never married, nor did he have children, and the site of his grave has been forgotten. But his patterns continue to inspire scientists and artists alike.
Rossing, T. American Journal of Physics. Ullmann, D. The Life and Work of E. Vuillermet, Gael et al. Chladni Patterns in a Liquid at Microscale. Physical Review Letters. Librarians Authors Referees Media Students. Login Become a Member Contact Us. Ernst Florens Friedrich Chladni Sand placed on a vibrating plate exhibit distinction patterns called Chladni figures.
This Month in Physics History
Leonardo da Vinci noted the unusual patterns formed by particles in response to vibrations. So did Galileo, who noticed that bits of bristle on the sounding board of an instrument would move in some areas but not in others. But these so-called "Chladni figures" bear the name of the man who conducted the first in-depth investigations of the phenomenon: a German physicist and musician named Ernst Florens Friedrich Chladni. Chladni was born in Wittenberg in , to a long line of academics. His father was a law professor and dean of law at the University of Wittenberg. Both his mother and his sister died when he was still quite young. Chladni was mostly educated at home by his father, a strict disciplinarian.
Ernst Chladni is regarded by many historians as the 'father of acoustics' for his seminal experimental work on vibrations. He was also a well respected musician and inventor of musical instruments. Ernst Chladni image 1 was born in Wittenberg, Germany. Chladni's father, who was a professor of law at the University of Wittenberg, disapproved of his son's early interests in music and science and forced him to study law.
Chladni, Ernst Florenz Friedrich
His most important work, for which he is sometimes labeled the father of acoustics , included research on vibrating plates and the calculation of the speed of sound for different gases. Although Chladni was born in Wittenberg in Saxony , his family originated from Kremnica , then part of the Kingdom of Hungary and today a mining town in central Slovakia. Chladni has therefore been identified as German ,   Hungarian  and Slovak. Chladni came from an educated family of academics and learned men.
Ernst Florens Friedrich Chladni was a physicist and musician. His work includes research on vibrating plates and the calculation of the speed of sound for different gases. For this some call him the "father of acoustics". He also did pioneering work in the study of meteorites, and therefore is regarded by some as the "father of meteoritics" as well.