题目内容
按图连接电路后,灯泡L不亮,用欧姆表检查灯泡L,发现L是好的,用电压表测得Ucd=Ubd=0,Uad="6" V。由此可断定该电路可能发生的故障是
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/201408241501563182827.jpg)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/201408241501563182827.jpg)
A.R1短路 | B.R2短路 | C.R1断路 | D.R2断路 |
C
试题分析:由题意可知
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824150156380617.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824150156536603.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824150156380617.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824150156786327.png)
故选C
点评:中等难度。判断方法:用电压表检测电路故障;(1)若电路中某两点电压不为零,说明电压表上有电流通过,则在并联路段之外无断路或并联电路内无短路; (2)若电路中某两点电压为零,说明电压表上无电流通过,则可能在并联路段之外有断路或并联电路内有短路.
![](http://thumb2018.1010pic.com/images/loading.gif)
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