题目内容
R1、R2两个电阻的U—I图线如图所示,则
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/201408250013240851435.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/201408250013240851435.png)
A.R 1 < R 2 |
B.它们并联的电阻阻值为R,则R的U I图线在图中区域Ⅰ |
C.它们并联的电阻阻值为R,则R的U I图线在图中区域Ⅱ |
D.若将它们并联在电路中,发热功率较大的是电阻R2 |
D
试题分析:由伏安特性曲线可知,直线的斜率即为电阻,所以
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/20140825001324101490.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/201408250013241171666.png)
两个电阻并联后,总电阻R更小,因此加相同的电压时,电流会更大,因此并联后的总电阻R一定在III区内,B、C错误;根据发热功率
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/20140825001324132622.png)
![](http://thumb2018.1010pic.com/images/loading.gif)
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