Stringed Instruments

Stringed instruments produce sound when an action such as plucking or bowing causes them to vibrate. When a string is fixed at both ends, two transverse waves will move from the left and right side of the disturbance. When the waves hit the fixed ends of the string, they bounce back and continue to vibrate until they are eventually stopped by friction and "leaks" through the fixed points. It can be proved with mathematics that standing waves are the only stable vibrations that are possible for a string with two fixed ends. Because these waves are standing waves, the only possible wavelengths are found by 2L/n, where L is the length of the string and n is the harmonic number, which is can be any integer describing the mode of the stretched string. The frequency can then be determined by multiplying 2L/n by the square root of the tension divided by the mass per unit length. The frequency of a vibrating string is 1) inversely proportional to its length, 2) directly proportional to the square root of the tension, and 3) inversely proportional to the square root to the mass per unit length. Waves with a higher frequency create a higher pitch. Therefore, to create a higher pitch on a stringed instrument you use your finger to fix the string farther down to make it shorter, use the tuning pegs to tighten the string, or play on a thinner string.

Tuning pegs used to tighten or loosen the string.

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