手击管产生的多谐波：一种简单而精确的声速测量方法

中文摘要 AI 辅助

空气声速可通过细圆柱管内谐波共振频率来确定。用张开的手多次敲击管的一端并保持手在原位，从而在管内产生压力波。这样产生的短脉冲沿管传播，并分解为谐波叠加，其频率由一端开口、另一端闭口的管中存在的谐波决定。管因此充当滤波器，增强在闭端具有声压波腹、在开端具有波节的谐波，这些波的频率由边界条件决定，而不同频率的波通过相消干涉相互抵消。用连接计算机的麦克风记录声音，并使用免费软件分析其频谱，可获得共振频率，从而以优于0.5%的精度确定声速。整个实验仅需一根管、一个麦克风和免费软件，因此成本低廉，设置仅需几分钟，非常适合基础物理实验室使用。

英文摘要

The speed of sound in air can be determined from the resonance frequencies of the harmonic waves inside a thin cylindrical tube. A pressure wave is generated in the tube by striking several times one of its ends with an open hand and keeping the hand in place. In this way pulses of short duration are produced which propagate along the tube and decompose into a superposition of harmonic waves whose frequencies are determined by the harmonics present in a tube open at one end and closed at the other. The tube thus acts as a filter that reinforces those harmonic waves exhibiting an antinode of acoustic pressure at the closed end and a node at the open end. Their frequencies are determined by these boundary conditions, while waves with different frequencies cancel out by destructive interference. Recording the sound with a microphone connected to a computer and analyzing its spectrum with freely available software, the resonance frequencies are obtained and the speed of sound is determined with an accuracy better than $0.5\%$. The whole experiment requires nothing but a tube, a microphone and free software, so it is inexpensive, takes a few minutes to set up and is well suited to introductory physics laboratories.

发表机构

• Instituto de Fisica, Universidad de la República（乌拉圭共和国大学物理研究所）

机构由 AI 辅助整理，请以论文原文为准。