# Tuning Forks

Topics: Resonance, Wave, Resonator Pages: 3 (996 words) Published: December 14, 2012
MEASURING THE FREQUENCIES OF TUNING FORKS

OBJECT:
The aims of this experiment are measuring the frequency of tuning fork that used in experiment and calculating the percentage error of its frequency. THEORY:
Sound is a longitudinal wave that travels through all forms of matter. The air molecules vibrate in the same direction as the sound wave moves. The modes of vibrations associated with resonance in objects like strings or air columns have patterns called standing waves. The resonance occurs when the standing wave moves in the opposite direction to the medium’s movements, or when it arises from the combination of reflection and interference such that the reflected waves interfere with the incident waves. Nodes are the places where the medium does not move with the minimum amplitude(zero). Antinodes are the points of maximum vibrations. A tuning fork is a metal instrument used as an acoustic resonator. Tuning forks are typically constructed of aluminum, steel or an alloy. The fork is a "U" shape with a handle extended from the bottom of the "U". It resembles a fork consisting of two prongs, or tines. When struck by another object, the fork's tines vibrate and produce sound waves as a result. British musician John Shore invented the tuning fork in 1711. The vibrations of the tuning fork are controlled by the elasticity and the inertia of the prongs of the fork. The complex vibrations of the tuning fork involve bending deformation of the prongs. Transverse motions of the prongs cause an up and down motion in the stem of the tuning fork.

Figure 1: Demonstration of tuning forks
When a vibrating tuning fork is placed near the top of the resonance tube, the sound waves will be reflected from the bottom of the tube with a 180-degree phase shift, the incident and reflected waves will constructively or destructively interfere with each other. If the tube is just at the right length, the incident and reflected waves will constructively interfere and have a...