题目内容
如图所示的电路中,当滑动变阻器滑动触头向左滑动时,正确的是:
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/201408241519337503281.jpg)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/201408241519337503281.jpg)
A.L1灯泡变亮 |
B.L2灯炮变亮 |
C.电压表读数变大 |
D.电流表读数变小 |
B
试题分析:当滑动变阻器滑动触头向左滑动时,滑动变阻器电阻减小,外电路总电阻减小,总电流增大,根据闭合电路欧姆定律,内电压增大,外电压减小,电压表读数减小,
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824151933766313.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824151933766313.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824151933766313.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824151934078341.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824151934078341.png)
故选B
点评:动态问题分析思路总体来说是按照先部分后整体再部分的顺序,要充分利用电路中不变部分的电阻不变的特点,间接地讨论电路变化部分.
![](http://thumb2018.1010pic.com/images/loading.gif)
练习册系列答案
相关题目
如图所示,滑动变阻器的滑动头置于正中央,闭合开关S后,M、N、P三灯的亮度相同,今将变阻器的滑动头缓慢向左移动,则三灯的亮度从亮到暗的排列顺序是
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/201408241539222541300.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/201408241539222541300.png)
A.M、N、P | B.M、P、N |
C.P、M、N | D.N、M、P |