题目内容
某理想变压器原、副线圈的匝数比为55∶9,原线圈所接电源电压按图示规律变化,副线圈接有一灯泡,此时灯泡消耗的功率为40 W,则下列判断正确的是( )
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/201408241207176084149.jpg)
图13-9
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/201408241207176084149.jpg)
图13-9
A.副线圈两端输出的电压为![]() |
B.原线圈中电流表的示数约为0.18 A |
C.变压器的输入、输出功率之比为55∶9 |
D.原线圈两端电压的瞬时值表达式为u=220sin100πt(V) |
B
根据变压器的原、副线圈的电压之比等于匝数之比,故副线圈两端输出的电压为
,A错;根据理想变压器知P1=P2,故有
,B选项正确,C错;原线圈两端电压的瞬时值表达式为
,D错.只有B选项正确.
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824120717795889.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824120717967833.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/201408241207181071062.png)
![](http://thumb2018.1010pic.com/images/loading.gif)
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