题目内容
如图是一个理想变压器,K为单刀双掷开关,P是滑动变阻器滑动触头,U1为加在原线圈两端电压,I1为原线圈上电流,则:
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824174305761587.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824174305761587.png)
A.保持U1及P的位置不变,K由a合向b,I1将增大 |
B.保持U1及P的位置不变,K由b合向a,R消耗的功率减小 |
C.保持U1不变,K合在a处,使P上滑,I1将增大 |
D.保持P的位置不变,K合在a处,若U1增大,I1将减小 |
A
试题分析:保持
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824174306011349.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824174306229562.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824174306463293.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824174306011349.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824174306931630.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824174306011349.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824174307337600.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824174306463293.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824174307337600.png)
故选A
点评:本题主要考查变压器的知识,要能对变压器的最大值、有效值、瞬时值以及变压器变压原理、功率等问题彻底理解,注意电压表和电流表测量的是有效值.
![](http://thumb2018.1010pic.com/images/loading.gif)
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