题目内容
甲、乙两个电源的的路端电压U和干路电流I的关系图象如图所示,若它们分别向两个定值电阻R甲、R乙供电,可推知正确的结论是
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/201408241445465583245.jpg)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/201408241445465583245.jpg)
A.若R甲=R乙,甲电源产生的电流一定比乙电源的大 |
B.若R甲<R乙,甲电源产生的电流一定比乙电源的大 |
C.若两电源的路端电压相等,则R甲一定大于R乙 |
D.若两电源的路端电压相等,则R甲可能等于R乙 |
C
试题分析:根据U-I图像的截距的物理意义分析
甲和乙的U-I图像在纵轴上的截距相等,说明两电源的电动势相等,在横轴上的截距甲的大于乙的,说明乙电源的内阻小于甲电源的内阻,即
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824144546574474.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824144546636478.png)
根据闭合回路欧姆定律
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824144546698613.png)
若
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824144547057509.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824144546698613.png)
根据串联电路电压关系
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824144547166689.png)
点评:对于U-I图像,直线的斜率表示电源的内阻,纵轴的截距表示电源的电动势,横轴的截距表示短路电流,即可求出电源的内阻
![](http://thumb2018.1010pic.com/images/loading.gif)
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