题目内容
如图所示,长L1宽L2的矩形线圈电阻为R,处于磁感应强度为B的匀强磁场边缘,线圈与磁感线垂直。将线圈以向右的速度v匀速拉出磁场,求:①拉力F大小;②拉力的功率P;③拉力做的功W;④线圈中产生的电热Q;⑤通过线圈某一截面的电荷量q。![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824153933002554.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824153933002554.png)
①
②
③
④
⑤![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824153934344607.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824153933377678.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824153933439707.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824153933876739.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824153933876739.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824153934344607.png)
试题分析:①导体切割磁感线产生感应电动势
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824153934406601.png)
由欧姆定律可得
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824153934531521.png)
线圈匀速运动则拉力与安培力相等
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824153934594545.png)
解得
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824153934656819.png)
②拉力的功率为
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824153934672958.png)
③拉力做的功为
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/201408241539349841079.png)
④由焦耳定律可得线圈中产生的电热
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/201408241539351241654.png)
⑤通过线圈某一截面的电荷量为
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/201408241539351861250.png)
点评:本题的关键掌握导体切割磁感线产生的感应电动势
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824153935264527.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824153935327556.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824153935389677.png)
![](http://thumb2018.1010pic.com/images/loading.gif)
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