题目内容
一自耦调压变压器(可看做理想变压器)的电路如图甲所示,移动滑动触头P可改变副线圈匝数.已知变压器线圈总匝数为1 900匝,原线圈匝数为1 100匝,接在如图乙所示的交流电源上,电压表为理想电表,则 ( )
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/2014082500474197912453.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/2014082500474197912453.png)
A.交流电源电压瞬时值的表达式为u=220sin 100πt V; |
B.P向上移动时,电压表的示数变大,最大显示示数为380![]() |
C.P向下移动时,原、副线圈的电流之比减小; |
D.P向下移动时,变压器的输入功率变大。 |
C
试题分析:由图像可知,交流电源电压瞬时值的表达式为u=220
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/20140825004742010377.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/20140825004742025712.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/201408250047420411534.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/20140825004742057685.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/20140825004742072636.png)
![](http://thumb2018.1010pic.com/images/loading.gif)
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