题目内容
如图所示,理想变压器的原副线圈的匝数比为4:1,原线圈接有u="311sin100πt" V的交变电压,副线圈上接有定值电阻R、线圈L、灯泡L1及理想电压表V,以下说法正确的是
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/201408241602538382543.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/201408241602538382543.png)
A.副线圈中电流的变化频率为50HZ |
B.灯泡L1两端电压为55V |
C.若交变电压u的有效值不变,频率增大,则灯泡L1的亮度将变暗 |
D.若交变电压u的有效值不变,频率增大,则电压表V的示数将减小 |
AC
试题分析:原线圈输入电压峰值为311V,有效值为
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824160254041789.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824160254134707.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824160254400816.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824160254524636.png)
点评:本题难度较小,掌握三个结论:输入电压决定输出电压、输出电流决定输入电流、输出功率决定输入功率
![](http://thumb2018.1010pic.com/images/loading.gif)
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