题目内容
如图所示测定表头内阻的电路,电源内阻不计,当电阻箱的电阻调到1200 Ω时,电流表指针偏转到满刻度;再把电阻箱的电阻调到3000 Ω时,电流表指针刚好指到满刻度的一半.
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/201408241645383891949.jpg)
(1)根据上述数据可求出电流表的内阻为_ __Ω;
(2)若这个电流表的满刻度值是500μA,要把它改装成量程为3 V的电压表,应串联一个电阻值为___ _Ω的分压电阻;
(3)为了核对改装成的电压表V,给你一个标准电压表V0,一个4.5 V的电池组E,一个最大阻值为1 kΩ的滑动变阻器R,开关S及若干导线.请画出符合要求的电路图。![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824164538545645.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/201408241645383891949.jpg)
(1)根据上述数据可求出电流表的内阻为_ __Ω;
(2)若这个电流表的满刻度值是500μA,要把它改装成量程为3 V的电压表,应串联一个电阻值为___ _Ω的分压电阻;
(3)为了核对改装成的电压表V,给你一个标准电压表V0,一个4.5 V的电池组E,一个最大阻值为1 kΩ的滑动变阻器R,开关S及若干导线.请画出符合要求的电路图。
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824164538545645.png)
(1)600Ω(2)5400Ω(3)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/201408241645387952326.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/201408241645387952326.png)
试题分析:(1)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824164539122808.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824164539543949.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824164540011630.png)
(2)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824164540245656.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824164540448623.png)
(3)电路图如图所示:
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/201408241645407602327.png)
点评:做本题的关键是知道电压表改装需要串联一个电阻分压
![](http://thumb2018.1010pic.com/images/loading.gif)
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