题目内容
如图所示,电源电动势E=3.2 V,电阻R=30 Ω,小灯泡L的额定电压UL=3.0 V,额定功率PL=4.5 W.当开关S接1时,电压表的读数为3 V,则当开关S接2时,灯泡发光的情况
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/201408241303226282062.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/201408241303227373028.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/201408241303226282062.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/201408241303227373028.png)
A.很暗,甚至不亮 |
B.正常发光 |
C.比正常发光略亮 |
D.有可能被烧坏 |
A
由闭合电路欧姆定律
,得
.当开关S接2时,
,
,得
,小于额定电压,很暗,甚至不亮,A对.
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824130322768698.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824130322799496.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824130322846781.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824130322877684.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824130322924606.png)
![](http://thumb2018.1010pic.com/images/loading.gif)
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