发布时间 : 星期五 文章（河北专版）2019中考物理总复习 滚动小专题（五）电阻的测量更新完毕开始阅读2a9010cba88271fe910ef12d2af90242a995ab6f
5．(2018·石家庄21县市模拟联考)图1是小明测量定值电阻R的阻值时，连接的实验电路(电路元件完好，接线柱接线牢固)．
(1)小明在未检查电路连接是否正确的情况下，闭合了开关，调节变阻器的滑片时，发现__电压表__(填“电流表”或“电压表”)示数保持不变．
(2)检查电路，发现有一条导线连接错误，请在连接错误的导线上打“×”并补画出正确的连线．
解：
(3)纠正错误后，继续实验．某次实验，当电压表示数为2.7 V时，电流表示数(如图2所示)为__0.18__A，则该定值电阻的阻值为__15__Ω.
【拓展】实验结束后，老师要他测量一只阻值约为100 Ω的电阻Rx的值．所提供的器材有：
①干电池两节 ②电流表(0～0.6 A、0～3 A)一只 ③电压表(0～3 V、0～15 V)一只 ④滑动变阻器(100 Ω 2 A)一只 ⑤电阻箱(0～9999 Ω 5 A)一只 ⑥开关和导线若干
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请你帮助他完成下面的步骤，要求在电表读数时，指针偏转超过最大刻度值的.
3(1)你选择的实验器材是：__①③⑤⑥__(填序号)
(2)根据所选器材，画出一个能反映测量方法的电路图．
解：
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