题目内容
如图所示,两个垂直纸面的匀强磁场方向相反.磁感应强度的大小均为B.磁场区域的宽度均为2a,一个直径为2a的导线圆环从图示位置沿x轴正方向匀速穿过两磁场区域,以逆时针方向为电流的正方向,则感应电流I与导线圆环移动距离x的关系图象正确的是( )![](http://thumb.1010pic.com/pic2/upload/papers/20140824/201408241409414772658.jpg)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/201408241409414777377.jpg)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/201408241409414772658.jpg)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/201408241409414777377.jpg)
选C.
设导线圆环移动距离为x时,圆环切割磁感线的有效长度为l,则有(
)2+(a-x)2=a2,l=2
,感应电动势E=Blv,E随x为非线性变化,故A、B均错;当线框一部分在右侧磁场区域,一部分在左侧磁场区域时,两部分同时切割反向磁场,因而感应电流增加,故C正确.
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824140941493176.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824140941586343.png)
![](http://thumb2018.1010pic.com/images/loading.gif)
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