题目内容
如图所示的电路中,电源的电动势E和内电阻r恒定不变,电灯L恰能正常发光,如果变阻器的滑片P向b端滑动,则( )
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/201408250016586011463.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/201408250016586011463.png)
A.电灯L更亮,电流表的示数增大 |
B.电灯L更亮,电流表的示数变小 |
C.电灯L变暗,电流表的示数变小 |
D.电灯L变暗,电流表的示数增大 |
B
试题分析:当电路中滑动变阻器的滑片P向b滑动时,总电阻R变大,由闭合电路的欧姆定律
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/20140825001658617573.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/20140825001658633533.png)
![](http://thumb2018.1010pic.com/images/loading.gif)
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