题目内容
如图是街头变压器给用户供电的示意图,此变压器视为理想变压器,输入端接入的电压
(V),输出电压通过输电线输送给用户,输电线的电阻用R表示,理想变压器原、副线圈的匝数比为10:1,题中电表均为理想交流表,则下列说法正确的是
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/201408241645106055833.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824164510278900.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/201408241645106055833.png)
A.V2表的读数为![]() |
B.A1表的示数随A2表的示数的增大而增大 |
C.副线圈中交流电的频率为100Hz |
D.用户端闭合开关S,则V2表读数不变,A1表读数变大,变压器的输入功率增大 |
BD
试题分析:根据原副线圈两端的电压表和线圈匝数比成正比,所以可得
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824164511448634.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824164511635648.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824164511869878.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824164512072451.png)
故选BD
点评:变压器两端输入功率取决于副线圈中的功率,这一点需要注意
![](http://thumb2018.1010pic.com/images/loading.gif)
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