Sound: Resonance in a tube

When an external source plays a frequency that matches one of the harmonic standing waves of an object, a resonance can occur within the object. Resonance involves the reinforcement of a wave due to synchronized reflection of the wave. These “perfect reflections” can be induced by manipulating the neighboring environment, and are often used in medicine, such as in Magnetic Resonance Imaging (MRI). Resonance is exemplified by a large amount of energy transfer to the object and a dramatic increase in amplitude.

To investigate resonance, an experiment is performed wherein a speaker plays sound towards a tube of length D=2.0 meters which is open at both ends. The frequency of the speaker can be adjusted. It is observed that for certain speaker frequencies standing sound waves are set up in the tube causing a large resonance. Assume the speed of sound is 343m/s.

Figure 1. The apparatus of the experiment. The speaker produces sound waves which travel through the tube.