题目内容
如图所示的电路中, U="120" V, 滑动变阻器R2的最大值为 200Ω, R1=100Ω.当滑片P滑至R2的中点时,a、b两端的电压为( )
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824145126826443.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824145126826443.png)
A.60 V | B.40 V | C.80 V | D.120 V |
B
试题分析:当滑片P滑至
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824145126873361.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824145126873361.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824145127528327.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824145126873361.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/201408241451277311254.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/201408241451278711000.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824145127949965.png)
故选B
点评:中等难度。必须依据串联电路的特点、性质和欧姆定律求解,与滑动变阻器有关的电路,常常把滑动变阻器看做两个电阻,滑片一侧是一个电阻,滑片另一侧是另一个电阻,再与其他电阻相连,这样再分析就容易很多.
![](http://thumb2018.1010pic.com/images/loading.gif)
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