题目内容
如图所示电路中AB两端加交流电压u=141sin157tV时,小灯泡发光。若AB间电压变换为如下四种情况时(小灯泡都没有被烧毁),可以使小灯泡亮度增加的是
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/201408241711203891657.jpg)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/201408241711203891657.jpg)
A.直流电压141V | B.直流电压100V |
C.交流电压u=141sin100tV | D.交流电压u=141sin314tV |
D
试题分析:电容器的作用是通交流,隔直流,通高频,阻低频,所以换成直流电压,灯泡不会亮,AB错误;根据公式
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824171120592586.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824171121044789.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824171121450776.png)
点评:做本题的关键是知道电容器的作用是通交流,隔直流,通高频,阻低频,
![](http://thumb2018.1010pic.com/images/loading.gif)
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