6.
测量电流表\(G_{1}\)的内阻\(r\)\({\,\!}_{1}\)采用图甲所示的电路。可供选择的器材如下:
\(①\)待测电流表\(G_{1}\):量程为\(0~5mA\),内阻约为\(300Ω\)
\(②\)电流表\(G_{2}\):量程为\(0~10mA\),内阻约为\(40Ω\)
\(③\)定值电阻\(R\)\({\,\!}_{1}\):阻值为\(10Ω\)
\(④\)定值电阻\(R\)\({\,\!}_{2}\):阻值为\(200Ω\)
\(⑤\)滑动变阻器\(R\)\({\,\!}_{3}\):阻值范围\(0~1000Ω\)
\(⑥\)滑动变阻器\(R\)\({\,\!}_{4}\):阻值范围\(0~20Ω\)
\(⑦\)电池\(E\):电动势约为\(1.5V\),内阻很小
\(⑧\)开关\(S\)及导线若干
\((1)\)定值电阻\(R\)\({\,\!}_{0}\)应选____,滑动变阻器\(R\)应选____。\((\)在空格内填写序号\()\)
\((2)\)实验步骤\((\)部分\()\)如下:
\(①\)闭合开关\(S\),移动滑片\(P\)至某一位置,记录\(G_{1}\)和\(G_{2}\)的读数,分别记为\(I\)\({\,\!}_{1}\)和\(I\)\({\,\!}_{2}\);
\(②\)多次移动滑片位置,记录各次\(G_{1}\)和\(G_{2}\)的读数;
\(③\)以\(I\)\({\,\!}_{1}\)为纵轴,\(I\)\({\,\!}_{2}\)为横轴,作出图线如图乙所示;
\(④\)根据\(I\)\({\,\!}_{1}-\)\(I\)\({\,\!}_{2}\)图线的斜率\(k\)及定值电阻\(R\)\({\,\!}_{0}\),得到待测电流表\(G_{1}\)的内阻表达式为\(r\)\({\,\!}_{1}=\)_______。\((\)用\(k\)、\(R\)\({\,\!}_{0}\)表示\()\)
\((3)\)若测定电流表\(G_{1}\)的内阻\(r\)\({\,\!}_{1}\)为\(290Ω\),用它改装成如图丙所示的多量程多用电表,电流、电压和电阻的测量均各有两个量程不同的挡位。\(1\),\(2\)两个挡位为电流表挡位,其中大量程是小量程的\(10\)倍。
![](https://www.ebk.net.cn/tikuimages/8/2017/700/shoutiniao21/3f605e496181a0352c7561e0affd8fd7.png)
\(①\)关于此多用电表,下列说法中正确的是_______。
A.当转换开关\(S\)旋至位置\(3\)时为电阻挡
B.当转换开关\(S\)旋至位置\(6\)时为电压挡
C.转换开关\(S\)旋至\(5\)的量程比旋至\(6\)的量程大
D.表笔\(A\)为红表笔,表笔\(B\)为黑表笔
\(②\)图中电池\(E\)\('\)的电动势为\(9.0V\),当把转换开关\(S\)旋至位置\(4\),在\(A\)、\(B\)之间接\(900Ω\)电阻时,表头\(G_{1}\)恰好半偏。已知实验操作及步骤都正确无误,则\(R\)\({\,\!}_{5}=\)_______\(Ω\),\(R\)\({\,\!}_{6}=\)_______\(Ω\)。