Acoustic resonance

An acoustic wave is an oscillation of pressure (longitudinal waves) that travels through a solid, liquid, or gas in a wave pattern. Longitudinal waves are waves that have the same direction of vibration as their direction of travel. Important quantities for describing acoustic waves are sound pressure, particle velocity, particle displacement and sound intensity. Acoustic waves travel with the speed of sound which depends on the medium they are passing through.

If a periodic force is applied to such a system, the amplitude of the resulting motion is greatest when the frequency of the applied force is equal to one of the natural frequencies of the system. This is often referred as resonance. The resonance frequency is essential in this experiment because the sound the wine glass makes when its rim is rubbed by a moistened finger is the resonance frequency sound of the glass with the specific amount of water.