题目内容
如图所示,闭合电键S,电压表的示数为U,电流表的示数为I,现向左调节滑动变阻器R的触头P,下列说法正确的是]
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/201408250018249484406.jpg)
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/201408250018249484406.jpg)
A.I 变大 |
B.U 变大 |
C.电阻R1的功率变大 |
D.电源的总功率变大 |
BC
试题分析:向左调节滑动变阻器,则滑动变阻器连入电路的总电阻增大,所以电路总电阻增大,故电路总电流减小,即电流表示数减小,A错误;电路路端电阻增大,则根据闭合回路欧姆定律可得,电路路端电压增大,即电压表示数增大,B正确;电路总电阻增大,电路总电流减小,故路端电压增大,而通过
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/20140825001824948361.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/20140825001824948361.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/20140825001824994327.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/20140825001825010606.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/20140825001824994327.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/20140825001825041453.png)
![](http://thumb2018.1010pic.com/images/loading.gif)
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