Creative-Commons-Photo.com

Tuning fork

A tuning fork is an acoustic resonator in the form of a two-pronged fork with the tines formed from a U-shaped bar of elastic metal, usually steel. It resonates at a specific constant pitch when set vibrating by striking it against a surface or with an object, and emits a pure musical tone after waiting a moment to allow some high overtones to die out. The pitch that a particular tuning fork generates depends on the length of the two prongs. Its main use is as a standard of pitch to tune other musical instruments. The main reason for using the fork shape is that it produces a very pure tone, with most of the vibrational energy at the fundamental frequency, and little at the overtones (harmonics), as is the case with other resonators.

They are commonly used to tune musical instruments, although electronic tuners also exist, and some musicians have perfect pitch. Tuning forks can be tuned by removing material off the tines (filing the ends of the tines to raise it or filing inside the base of the tines to lower it) or by sliding weights attached to the prongs. Once tuned, a tuning fork's frequency varies only with changes in the elastic modulus of the material; for precise work, a tuning fork should be kept in a thermostatically controlled enclosure. Tuning forks can be driven electrically, by placing electromagnets close to the prongs that are attached to an electronic oscillator circuit, so that their sound doesn't die out.

HTML Code - Websites & Blogs
(original)
(thumbnail)

IMG Code - Forums & Bulletin Boards
(original)
(thumbnail)