题目内容
如图实-7-14甲所示,电压表V1、V2串联接入电路中时,示数分别为6 V和4 V,当只有电压表V2接入电路中时,如图实-7-14乙所示,示数为9 V,电源的电动势为( )
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/201408241415096862672.jpg)
图实-7-14
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/201408241415096862672.jpg)
图实-7-14
A.9.8 V | B.10 V | C.10.8 V | D.11.2 V |
C
设电源的电动势和内阻分别为E和r,电压表V2的内阻为R2,根据闭合电路欧姆定律,对图甲和图乙分别有:E=6+4+
r,E=9+
r,解得:E=10.8 V.故只有选项C正确.
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824141509702447.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824141509764466.png)
![](http://thumb2018.1010pic.com/images/loading.gif)
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