The phenomenon of beats can be observed directly on the double-channel oscillograph and the frequency of alternating current can be measured by the vibration curve of the beats.

在双通道示波器上可直观地观测拍现象，并利用拍振动曲线测量交流电的频率。

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The control effect of electromagnetic force on cylinder wake, lift force and drag force , which was caused by alternating current, is related to its frequency.

而交流电所产生的电磁力对于绕流涡街、升力、阻力的控制作用，则与所使用的频率有关。

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The system may measure many circuits high - frequency alternating current , direct current , frequency, efficiency of inverter .

系统测试项目有多路高频交流电流，直流电流，频率，逆变器的效率等。

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Although they have not been found to cause any harm, the cables on conventional pylons, which transmit a three-phase alternating current, generate a strong electric field and a continuous buzz of low-frequency radio waves.

ECONOMIST: Monitor