题目内容
在研究微型电动机的性能时,应用如图所示的实验电路.当调节滑动变阻器R使电动机停止转动时,电流表和电压表的示数分别为0.50A和2.0V.重新调节R使电动机恢复正常运转,此时电流表和电压表的示数分别为2.0A和24.0V,则这台电动机正确运转时的输出功率为( )
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/201408250020573133064.jpg)
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/201408250020573133064.jpg)
A.44W | B.32W |
C.47W | D.48W |
B
试题分析:从电路图中可以看出,电动机和滑动变阻器串联,电压表测量电动机两端的电压,电流表测量电路电流.电动机停止转动时,电能全部转化为内能,电路是纯电阻电路,欧姆定律成立,由电流表和电压表的示数,根据欧姆定律得:电动机的电阻
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/201408250020573291002.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/201408250020573601106.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/201408250020573751180.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/20140825002057391865.png)
![](http://thumb2018.1010pic.com/images/loading.gif)
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