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【题目】现有一个电学黑箱,有ABCD四个接线柱,如图所示。若用多用电表的电压挡和电阻挡分别做三次测量,发现两接线柱间测量结果如下:UABUACUAD1.5 VUBCUBDUCD0RBC4 ΩRBD3 ΩRCD5 Ω。试判断箱内电路的最简结构电阻无并联的情况

【答案】见解析

解析】由电压测量结果知,BCD三点电势相等,A点电势比它们高1.5 V,只有一节干电池,接线柱A应接电源正极,在BCD三点间无电池。

由电阻测量结果可知,BCD三个接线柱之间均有电阻,如图所示,由测量结果可知:R1R24 ΩR1R33 ΩR2R35 Ω,解得:R11 ΩR23 ΩR32 Ω

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