Oscillating electric currents through a wire under tension can excite transverse vibrational modes of the wire when a perpendicular static magnetic field is present and the frequency of the current is close to the natural frequency of the mode of interest. The excitation of the mode is associated with temporally oscillating Maxwell stresses on the wire, often also known as oscillating Lorentz forces. That excitation process is sometimes demonstrated in educational contexts. The investigation here concerns situations where a temporally oscillating magnetic field generated by oscillating electric currents in a cylindrical coil replaces the imposed perpendicular static magnetic field. The frequencies of the currents in the wire and in the coil are related to the frequency of the oscillating stress. In this experiment, this effect is documented for sum-frequency excitation (with input frequencies in the range of half that of the excited lowest vibrational mode of the wire) and the difference-frequency excitation (with input frequencies an order-of-magnitude larger than the mode frequency). This coupling may be useful when it is desirable to use only high-frequency currents. The experiment uses tone-burst stress excitation and a differential photodiode for detecting transverse low-amplitude wire oscillations. Signal envelopes decayed exponentially after the tone-burst.

中文翻译：

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分开电路中电流的差和总频率下的线振动的麦克斯韦应力激发

当存在垂直静磁场并且电流的频率接近感兴趣模式的固有频率时，在张力下通过电线的振荡电流会激发电线的横向振动模式。该模式的激发与导线上的麦克斯韦应力在时间上振荡有关，该应力通常也称为振荡洛伦兹力。有时在教育环境中证明了这种激发过程。这里的研究涉及这样的情况，在这种情况下，通过在圆柱线圈中振荡电流而产生的时间振荡磁场会替代所施加的垂直静磁场。导线和线圈中电流的频率与振荡应力的频率有关。在这个实验中 记录了这种影响，包括和频励磁（输入频率在导线的最低振动模态的一半范围内）和差频励磁（输入频率的数量级大于模态频率） ）。当只需要使用高频电流时，这种耦合可能有用。该实验使用音爆应力激励和差分光电二极管来检测横向低振幅导线的振荡。音频突发后，信号包络呈指数衰减。当只需要使用高频电流时，这种耦合可能有用。该实验使用音爆应力激励和差分光电二极管来检测横向低振幅导线的振荡。音频突发后，信号包络呈指数衰减。当只需要使用高频电流时，这种耦合可能有用。该实验使用音爆应力激发和差分光电二极管来检测横向低振幅导线的振荡。音频突发后，信号包络呈指数衰减。