题目内容
正弦式电流经过匝数比为
=
的变压器与电阻R、交流电压表 V、交流电流表A按如图6甲所示方式连接,R=10 Ω.图乙所示是R两端电压U随时间变化的图象,Um=10
V,则下列说法中正确的是 ( )
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/201408241416184206717.jpg)
A.通过R的电流iR随时间t变化的规律是iR=
cos100πt(A)
B.电流表A的读数为0.1 A
C.电流表A的读数为
A
D.电压表的读数为Um=10
V
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824141617936411.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824141618014346.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824141618061344.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/201408241416184206717.jpg)
A.通过R的电流iR随时间t变化的规律是iR=
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824141618061344.png)
B.电流表A的读数为0.1 A
C.电流表A的读数为
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824141618482468.png)
D.电压表的读数为Um=10
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824141618061344.png)
AB
由图乙所示图象知T=2×10-2 s,f=50 Hz,ω=2πf=100π rad/s,Im=
=
A,故iR=
cos100πt(A),A正确.再根据
=
,I2=
=1 A知,I1的有效值为0.1 A,B正确,C错误.电压表读数应为副线圈电压的有效值,U=
=10 V,故D错误.
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824141618685525.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824141618061344.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824141618061344.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824141618856411.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824141618919418.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824141618997518.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824141619044553.png)
![](http://thumb2018.1010pic.com/images/loading.gif)
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