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1、简答题 待测电阻Rx的阻值约为几百欧,甲、乙两位同学分别用不同的器材对其进行了测量:
甲同学采用如图所示的电路,电流表内阻很小,电压表内阻很大.当开关S闭合时,电压表示数为6.0V,电流表示数为15mA,则Rx=______Ω.
乙同学选用的器材有:
电流表A1与A2,量程均为0~50mA,内阻可忽略;
定值电阻R0一个,阻值为600Ω;
滑动变阻器R一个,阻值为10Ω;
电源E一个,开关S一个,导线若干.
①要求测量几组数据,且每组数据中电流表的读数都有较大变化,试在方框内画出测量电阻Rx的实验电路原理图(原理图中的元件用题干中相应的英文字母标注).
②若某次测量中与电阻Rx串联的电流表A1的示数为I1,另一个电流表A2的示数为I2.则由已知量和测量量计算Rx的表达式为Rx=______.
2、选择题 用图示的电路可以测量电阻的阻值.图中Rx是待测电阻,R0是定值,G是灵敏度很高的电流表,MN是一段均匀的电阻丝.闭合开关,改变滑动头P的位置,当通过电流表G的电流为零时,测得MP=l1,PN=l2,则Rx的阻值为( )
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B.style="shiti/data:image/png;base64,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" alt="">R0
C.style="shiti/data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAAA8AAAAsCAIAAAA1jHWFAAAA6UlEQVQ4jc2TvR2DIBDF3xaMYXFDZAoadnAIGkbIDDY3QVagYQO2IAWaKAcGC/PjKsW/9+6Dh3QlcD/N1gBwS+jMHc00sY9ddPQ8TeYHu6/EWN5EFACAZFkr7fQjl8F2zg9OkxJqmQ4kMkXPShwipRQWR9oJ2UoKZFE5u+h5Xjs50IFAL/Htaa0cEaJnBRQNsTXVTVU2v5tmsEfBknaa8A1VbPcPd3AEuic2OF7IHT1foJ2mLjrfjn1NXTGy5zvoj+e3V6r+XPF87rhJS8+3Cqt7/oSueL5Jtzx/0mUZt9F5gtUhDuTiYeg3HTHzCt2WixAAAAAASUVORK5CYII=" alt="">R0
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