题目内容
如图所示,当变阻器滑动片向下滑动时,下列判断正确的是
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/201408241445433444465.jpg)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/201408241445433444465.jpg)
A.L1、L2灯都变暗 |
B.L1、L2灯都变亮 |
C.L1灯变亮, L2灯变暗 |
D.L1灯变暗,L2灯变亮 |
A
试题分析:从变动的部分到整体,再到其他部分的规律分析
电路可以看做两个并联电路,其中L1一个支路,另一个支路为:L2与滑动变阻器并联后与定值电阻串联。当滑动变阻器的划片向下滑动时,滑动变阻器连入电路的电阻减小
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824144543376223.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824144543376223.png)
路端电压减小
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824144543376223.png)
L1两端的电压减小
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824144543376223.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824144543376223.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824144543376223.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824144543376223.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824144543376223.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824144543376223.png)
点评:在分析该类问题时,要善于把部分电路和全电路结合起来,按变动部分
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824144544702235.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824144544702235.png)
![](http://thumb2018.1010pic.com/images/loading.gif)
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