题目内容
如图所示,等腰直角三角形
内部存在着垂直纸面向里的均匀磁场,它的
边在
轴上且长为
纸面内一边长为
的正方形导线框的一条边在
轴上,且导线框沿
轴正方向以恒定的速度
穿过磁场区域,在
时该导线框恰好位于图甲中所示的位置。现规定逆时针方向为导线框中感应电流的正方向,在图乙所示的四个
图象中,能正确表示感应电流随导线框位移变化关系的是( )![](http://thumb.1010pic.com/pic2/upload/papers/20140824/201408241241461722747.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/2014082412414621816599.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824124145766434.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824124145782366.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824124145813272.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824124145844360.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824124145860271.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824124145813272.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824124145813272.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824124146062277.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824124146109344.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824124146140342.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/201408241241461722747.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/2014082412414621816599.png)
B
线框进入磁场时,有效切割长度恒定,产生恒定的电动势E=BLV,所以排除C选项,全部进入磁场后瞬时感应电动势为零,且电流方向发生改变,此时已能确定B选项正确(随着线框向右匀速运动,有效切割长度均匀增大,感应电流也均匀增大,当线框运动2L时,感应电流达到最大值,之后有效切割长度均匀减小,感应电流也均匀减小,运动3L时,瞬时感应电流减为零,故B正确
故选B
故选B
![](http://thumb2018.1010pic.com/images/loading.gif)
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