【摘要】 弦振动实验不仅可以研究弦受迫振动时的振幅变化，还可以研究相位变化，特别是共振时的相位变化.本文对弦振动的简化模型进行了微分方程建模，研究了弦线在受迫振动时幅值与相位的变化规律.采用共振法和相位法测得弦线共振频率，计算得到弦的线密度，2种方法测得的实验值均与理论值符合较好.该实验不仅可以拓展弦振动实验，还可以进一步加深学生对共振现象的理解.更多还原

【Abstract】 The string vibration experiment can be used as a basis to not only study the amplitude change of the wave during forced vibration, but also the phase change of the wave, especially the phase of wave at resonance. In this paper, the differential equation was established to research the amplitude and phase of forced string vibration by using a simplified model of string vibration. The resonance frequency of string was measured by resonance method and phase method, and then the linear density of string was calculated. The experimental values measured by the two methods were in good agreement with the theoretical values. This experiment could not only expand the string vibration experiment, but also further deepen the students’ understanding of resonance phenomenon.更多还原