题目内容
在如图所示的电路中,E为内阻不可忽略的电源,R 1、R2为定值电阻,R为光敏电阻.无光照射时,外电路的总电阻比电源的内阻小;当有光照射在光敏电阻上,且照射光的强度逐渐增大时,下列说法正确的是[ ]
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/2014082500352476817459.jpg)
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/2014082500352476817459.jpg)
A.电源消耗的总功率减少 |
B.外电路消耗的功率逐渐减少 |
C.外电路消耗的功率先增大后减少 |
D.电压表的读数增大,电流表的读数减小 |
B
试题分析:光敏电阻在被光照时,阻值随光强增大而减小,电路总电阻减小,干路电流增大,根据公式
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/20140825003524784477.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/201408250035249241261.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/20140825003524955360.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/20140825003524971279.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/20140825003525189569.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/20140825003525314361.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/20140825003525314361.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/20140825003525314361.png)
![](http://thumb2018.1010pic.com/images/loading.gif)
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