题目内容
如图所示,一台理想变压器的原线圈和副线圈的匝数比为n1∶n2=1∶2,原线圈接在交流电压220伏上.Q为保险丝,其允许通过的电流不超过2安;R为负载电阻.那么变压器正常工作时,R的阻值应( )
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/201408241518108213184.jpg)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/201408241518108213184.jpg)
A.不高于220欧 | B.不高于440欧 |
C.不低于220欧 | D.不低于440欧 |
D
试题分析:利用理想变压器的变压、变流规律得出副线圈的电压和电流值,由欧姆定律计算负载电阻的大小。
有理想变压器原副线圈电压比与匝数比的关系有:
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824151810836653.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824151810930907.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824151810992614.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824151811101780.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824151811211829.png)
故选D
点评:注意理想变压器的变压关系是一个普适关系,而电流比
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824151810992614.png)
![](http://thumb2018.1010pic.com/images/loading.gif)
练习册系列答案
相关题目