PURPOSE: To hear sympathetic vibrations.
DESCRIPTION: Two matched Tuning forks are used, as shown in the above left photo. One tuning fork is tapped lightly with a rubber mallet so it vibrates, as shown in the above middle photo. Grasp the other tuning fork by the base, turn it upside down and place the fork very close to the vibrating fork, as shown in the above right photo. Hold it there for a moment, but do not let the forks touch. Once it is vibrating in sympathy, place the tuning fork very close to an audio pick up coil connected to an amp and speaker and project the sympathetic vibrations to the class (pick up, amp and speaker are not shown in the photo).
EQUIPMENT: Matched tuning forks, as photographed.
SETUP NOTES: Please be careful with these tuning forks. They have historical value.
The Tuning Forks in the Brown U. Physics demonstration collection have a high degree of historical value. They were made by the world famous tuning fork manufacurer, Rudolf Koenig. The collection in the demo room is now limited. Today we provide a very small range of frequencies for classroom use. Most of the original collection has been archived. A collection of acoustic brass Helmholtz Resonators is located in the history of science display on the 2nd floor. These were also made by RK and were used in conjunction with his tuning forks.
Rudolf Koenig (1832- 1901) was born and educated in Koenigsberg, East Prussia (currently Kaliningrad, Russia). Inspired by Herman von Helmholtz in 1858 Koenig started his own business building acoustical instruments for physicists. He quickly gained an international reputation for the quality, precision and beauty of his instruments. In 1862 and in 1876, Koenig won Gold Medals at the London and the Philadelphia exhibitions. Albert Michelson used a Koenig tuning fork to determine the speed of a revolving mirror, which was part of the apparatus for measuring the velocity of light. For more information about Rudolf Koenig and his Helmholtz Resonators and Tuning Forks please visit the Brass Instrument Psychology Museum at the University of Toronto:
http://www.psych.utoronto.ca/museum/
Updated by Jun Qi in 4/5/2000