题目内容
(10分)某同学要测定一个圆柱体的电阻率,进行了如下操作:
(1)(2分)用10分度的游标卡尺测量圆柱体的长度,由图可知其长度为 mm;
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/201408241535232779444.png)
(2)(2分)用螺旋测微器测量其直径如图,可知其直径为 mm;
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/201408241535233862383.png)
(3)(2分)用已调零且选择旋钮指向欧姆挡“×1”位置的多用电表粗略测量该圆柱体的电阻,根据图所示的表盘,可读出被测电阻阻值为______Ω
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/201408241535241826987.png)
(4)(4分)为了精确的测量该圆柱体的电阻,他选用了以下仪器,用伏安法进行测量,实验要求电压表的读数从0开始,请在框图中画出实验电路图。
E.开关、导线若干![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824153524463610.png)
(1)(2分)用10分度的游标卡尺测量圆柱体的长度,由图可知其长度为 mm;
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/201408241535232779444.png)
(2)(2分)用螺旋测微器测量其直径如图,可知其直径为 mm;
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/201408241535233862383.png)
(3)(2分)用已调零且选择旋钮指向欧姆挡“×1”位置的多用电表粗略测量该圆柱体的电阻,根据图所示的表盘,可读出被测电阻阻值为______Ω
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/201408241535241826987.png)
(4)(4分)为了精确的测量该圆柱体的电阻,他选用了以下仪器,用伏安法进行测量,实验要求电压表的读数从0开始,请在框图中画出实验电路图。
A.直流电源,输出电压为6V; |
B.电压表3V,内阻大约1kΩ; |
C.电流表0.6A,内阻大约1Ω; |
D.滑动变阻器,总电阻10Ω; |
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824153524463610.png)
(1)(2分) 22.6 (2)(2分) 6.360-6.363
(3)(3分) 7 (4)(3分)如下图所示
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/201408241535246032239.png)
(3)(3分) 7 (4)(3分)如下图所示
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/201408241535246032239.png)
试题分析:(1)由图得主尺读数为2.2cm=22mm,游标尺读数为
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824153524697675.png)
由图得主尺读数为6mm,可动刻度读数为
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824153524806814.png)
由图知,电阻读数要读多用电表最上的表盘,即读数为
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824153525009543.png)
由题意要求电压表的读数从0开始,所以滑动变阻器要用分压接法,由待测电阻大约为7欧,满足电压表的内阻远大于待测电阻,得电流表要用外接法,具体电路图见答案。
点评:学生要会读游标卡尺、螺旋测微器、多用电表的示数,知道滑动变阻器必须用分压接法的三种情况。
![](http://thumb2018.1010pic.com/images/loading.gif)
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