题目内容
如图所示,电阻
,小灯泡
上标有“3V,1.5W",电源内阻
,滑动变阻器的最大阻值为R0(大小未知),当触头
滑动到最上端
时,安培表的读数为l A,小灯泡
恰好正常发光,求:
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/201408241303071214201.jpg)
小题1:滑动变阻器的最大阻值R0
小题2:当触头
滑动到最下端
时,求电源的总功率及输出功率。
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824130306918527.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824130306950279.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824130306996445.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824130307012289.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824130307043278.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824130306950279.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/201408241303071214201.jpg)
小题1:滑动变阻器的最大阻值R0
小题2:当触头
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824130307012289.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824130307168299.png)
小题1:
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824130307184805.png)
小题2:
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824130307215796.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824130307230883.png)
(1)当触头
滑动到最上端
时,流过小灯泡
的电流为:![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824130307340788.png)
流过滑动变阻器的电者呐:
故:![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824130307184805.png)
(2)电源电动势为:
当触头
,滑动到最下端
时,滑动交阻器和小灯泡均被短路.电路中总电流为:
故电源的总功率为:![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824130307215796.png)
输出功率为:![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824130307230883.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824130307012289.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824130307043278.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824130306950279.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824130307340788.png)
流过滑动变阻器的电者呐:
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824130307371710.png)
故:
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824130307184805.png)
(2)电源电动势为:
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824130307464987.png)
当触头
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824130307012289.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824130307168299.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824130307574805.png)
故电源的总功率为:
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824130307215796.png)
输出功率为:
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824130307230883.png)
![](http://thumb2018.1010pic.com/images/loading.gif)
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