电磁打点计时器和电火花打点计时器都是使用_1（填“直流”或“交流”）电源的计时仪器，使用打点计时器时要先_2（填“接通电源”或“让纸带开始运动”）再_3（填“接通电源”或“让纸带开始运动”）．若已知电_刷题宝

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电磁打点计时器和电火花打点计时器都是使用____（填“直流”或“交流”）电源的计时仪器，使用打点计时器时要先____（填“接通电源”或“让纸带开始运动”）再____（填“接通电源”或“让纸带开始运动”）．若已知电源频率为50Hz，则打点计时器在纸带上打相邻两点的时间间隔为____s．

上一题下一题 0.0难度选择题更新时间:2019-10-02 11:49:18

答案(点此获取答案解析）

交流,接通电源,让纸带开始运动,0.02

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