Measuring the Speed of Sound. A student investigator is measuring the speed of sound by looking at the time for a brief, sinusoidal pulse from a loudspeaker to travel down a tube, reflect from the closed end, and reach a microphone. The apparatus is shown in the figure (a); typical data recorded by the microphone are graphed in the figure (b). The first pulse is the sound directly from the loudspeaker; the second pulse is the reflection from the closed end. A portion of the returning wave reflects from the open end of the tube and makes another round trip before being detected by the microphone; this is the third pulse seen in the data.
What was the approximate frequency of the sound wave used in this experiment?
What can you say about the reflection of sound waves at the ends of a tube?
What was the approximate length of the tube?
An alternative technique to determine sound speed is to measure the frequency of a standing wave in the tube. What is the wavelength of the lowest resonance of this tube?