Tuning fork on resonance box, by Max Kohl, Chemnitz, Germany

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). A resonator is a device or system that exhibits Resonance or resonant behavior that is it naturally oscillates at some frequencies, called its resonance As a piece of Cutlery or Kitchenware, a fork is a tool consisting of a handle with several narrow tines (usually two three or four on one end Tines or prongs are parallel or branching spikes forming parts of various tools and natural objects In Materials science, deformation is a change in the shape or size of an object due to an applied force. Steel is an Alloy consisting mostly of Iron, with a Carbon content between 0 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. In Physics, resonance is the tendency of a system to Oscillate at maximum Amplitude at certain frequencies, known as the system's Pitch represents the perceived Fundamental frequency of a sound An overtone is a natural resonance or vibration frequency of a system The pitch that a particular tuning fork generates depends on the length of the two prongs.

## Explanation

Currently, the most common tuning fork used by musicians sounds the note of A (440 Hz, international "concert pitch"), which has long been used as a standard tuning note by orchestras, it being the pitch of the violin's second string played open, the first string of the viola played open, and an octave above the first string of the cello, again played open. A440 is the 440 Hz tone that serves as the standard for musical pitch. However, they are also commercially made to vibrate at frequencies corresponding to all musical pitches within the central octave of the piano, and other pitches.

Tuning fork by John Walker showing note (E) and frequency in hertz (659)

The tuning fork was invented in 1711 by John Shore, Sergeant Trumpeter to the court, who had parts specifically written for him by both George Frideric Handel and Henry Purcell. Year 1711 ( MDCCXI) was a Common year starting on Thursday (link will display the full calendar of the Gregorian calendar (or a John Shore (c 1662 - 1752 was an English trumpeter and the inventor of the Tuning fork, which he invented in 1711 Henry Purcell (ˈpɜrsəl 10 September 1659 (? – 21 November 1695 was an English Baroque Composer.

The reason for using the fork shape is that, when vibrating, there is a node in the vibration pattern at the bend of the 'U' where the handle is attached, so the handle doesn't vibrate. A node is a point along a Standing wave where the wave has minimal Amplitude. This allows it to be held there without damping the vibration.

When struck, it gives out a very faint note which is barely audible unless held close to the ear. The ear is the sense organ that detects Sounds The Vertebrate ear shows a common biology from Fish to Humans with variations For this reason, it is sometimes struck and then pressed down on a solid surface such as a desk which acts as a sounding board and greatly amplifies the note. The sounding board or soundboard is the part of a String instrument that transmits the vibrations of the strings to the air greatly increasing the Loudness

Well-known manufacturers of tuning forks include Ragg and John Walker, both of Sheffield, England. Sheffield ( is a city and Metropolitan borough in South Yorkshire, England England is a Country which is part of the United Kingdom. Its inhabitants account for more than 83% of the total UK population whilst its mainland

## Calculation of frequency

The frequency of a tuning fork depends on its dimensions and the material from which is made: [1]

$f \propto \frac{1}{l^2} \sqrt{\frac{AE}{\rho}}$, and where the tines are cylindrical,[2] $f = \frac{R}{\pi l^2} \sqrt{\frac{E}{\rho}}$

Where:

• f is the frequency the fork vibrates at
• A is the cross-sectional area of the tuning fork
• l is the length of the fork's tines
• E is the Young's modulus of the material the fork is made from
• ρ is the density of the material the fork is made from
• R is the radius of the tines

## Uses

They are commonly used to tune musical instruments, although electronic tuners also exist, and some musicians have perfect pitch. A cylinder is one of the most basic curvilinear geometric shapes the Surface formed by the points at a fixed distance from a given Straight line, the axis Frequency is a measure of the number of occurrences of a repeating event per unit Time. Area is a Quantity expressing the two- Dimensional size of a defined part of a Surface, typically a region bounded by a closed Curve. Length is the long Dimension of any object The length of a thing is the distance between its ends its linear extent as measured from end to end In Solid mechanics, Young's modulus (E is a measure of the Stiffness of an isotropic elastic material The density of a material is defined as its Mass per unit Volume: \rho = \frac{m}{V} Different materials usually have different Tines or prongs are parallel or branching spikes forming parts of various tools and natural objects In Music, there are two common meanings for tuning: Tuning practice, the act of tuning an instrument or voice A musical instrument is a device constructed or modified for the purpose of making Music. An electronic tuner is a device used by Musicians to detect and display the pitch of notes played on Musical instruments The simplest tuners indicate Absolute pitch (AP widely referred to as perfect pitch, is the ability of a person to identify or recreate a Musical Note without the benefit of a known 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. An elastic modulus, or modulus of elasticity, is the mathematical description of an object or substance's tendency to be deformed elastically (i Large forks are often made to be driven electrically, like an electric bell or buzzer, and can vibrate for an indefinite time.

### In musical instruments

A number of keyboard musical instruments using constructions similar to tuning forks have been made, the most popular of them being the Rhodes piano, which has hammers hitting constructions working on the same principle as tuning forks. A keyboard instrument is any musical instrument played using a Musical keyboard. A Rhodes piano is an electromechanical Musical instrument, a brand of Electric piano.

### In electromechanical watches

Electromechanical watches developed by Max Hetzel for Bulova used a 360 Hertz tuning fork with a battery to make a mechanical watch keep time with great accuracy. Bulova is a New York based corporation making Watches and Clocks. The production of the Bulova Accutron, as it was called, ceased in 1977.

A tiny quartz tuning fork is used in crystal oscillators, the most notable use of which are quartz digital watches. Quartz (from German) is the most abundant Mineral in the Earth 's Continental crust (although Feldspar is more common in A crystal oscillator is an Electronic circuit that uses the mechanical Resonance of a vibrating Crystal of piezoelectric material to create an A watch is a timepiece that is made to be worn on a person The term now usually refers to a wristwatch, which is worn on the wrist with a strap or Bracelet. The piezoelectric properties of quartz crystals cause a quartz tuning fork to generate a pulsed electrical current as it resonates, which is used by the computer chip in the watch to keep track of the passage of time. Piezoelectricity is the ability of some materials (notably Crystals and certain Ceramics including bone to generate an Electric potential in response to In Materials science, a crystal is a Solid in which the constituent Atoms Molecules or Ions are packed in a regularly ordered repeating Microchipsjpg|right|thumb|200px|Microchips ( EPROM memory with a transparent window showing the integrated circuit inside For other uses see Time (disambiguation Time is a component of a measuring system used to sequence events to compare the durations of In today's watches, they generally resonate at 215 = 32,768 Hz. The hertz (symbol Hz) is a measure of Frequency, informally defined as the number of events occurring per Second. (See quartz clock. A quartz clock is a Clock that uses an Electronic oscillator that is regulated by a Quartz crystal to keep time )

### Medical uses

Main article: Hearing test

Tuning forks, usually C-512, are used by medical practitioners to assess a patient's hearing. A hearing test is an evaluation of the sensitivity of a person's sense of hearing, most often performed by an Audiologist using an Audiometer. Lower-pitched ones (usually C-128) are also used to check vibration sense as part of the examination of the peripheral nervous system.

Tuning forks also play a role in several alternative medicine modalities, such as sonopuncture and polarity therapy. The term alternative medicine, as used in the modern western world encompasses any healing practice "that does not fall within the realm of conventional Medicine. Polarity therapy is a " holistic " health system developed by Randolph Stone.

### Radar gun calibration

A radar gun, typically used for measuring the speed of cars or balls in sports, is usually calibrated with tuning forks. A radar gun or speed gun is a small Doppler radar used to detect the speed of objects Instead of the frequency, these forks have the calibration speed and radar band (e. g. X-Band or K-Band) for which they are calibrated.