Nodal Lines Experiment

The geometric patterns of figures are formed by the nodal lines; lines formed where opposite vibrations meet to form the point of no vibrations. This experiment was previously done by Robert Hooke and more famously done by Ernest Chladni, thus the Chladni plate experiment. The nodal lines form when a frequency travels as vibration through the metal. As the vibration travels throughout, it reaches the end of the metal plate and bounce back, and when it does, it meets the newly traveling vibration formed by the frequency. This location where the opposite vibration meets has no vibration because the vibrations cancel each other out. Thus the nodal lines are created as the vibration travels back and forth through the metal plate. The shapes are formed by very tiny material used such as sand, sugar, or salt. These material travel with the vibration until reaching the nodal line where they stop, and the formation produced by the materials give the geometric lines and shapes on the metal plate. To produce enough frequency to create the vibrations needed to move the material across the metal plate, Ernest Chladni directly applied the frequency with a violin bow, but this can also be applied with any sort of sound or vibration applying source. The study of visible sound such as the chladni figures on the metal plate, is called the cymatics and the study of the nodal lines is closely related to the formation of harmonics which relies on the vibrating of a string. The understanding of the nodal figures at different frequencies helps to improve instrument designs and understand the working of sound.

^ Ernst Florens Friedrich Chladni, German physicist, 1802 Image Preview, Science and Society Picture Library

Jump up ^ Good Vibrations, Joyce McLaughlin, American Scientist, July–August 1998, Volume: 86 Number: 4 Page: 342, doi:10.1511/1998.4.342