题目内容
用电压表、电流表测定a、b两节干电池的电动势Ea、Eb和内电阻ra、rb时,画出的图线如图所示,则由此图线可知( )
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/201408241519579622965.jpg)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/201408241519579622965.jpg)
A.Ea>Eb、ra>rb | B.Ea>Eb、ra<rb |
C.Ea<Eb、ra>rb | D.Ea<Eb、ra<rb |
A
试题分析:据
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824151958071569.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824151958149548.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824151958352515.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824151958414456.png)
故选A
点评:利用U-I图象求解电动势和内阻时要注意:图线的斜率为电源的内电阻,即
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824151958476649.png)
![](http://thumb2018.1010pic.com/images/loading.gif)
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