题目内容
如图所示,相距为d的两条水平虚线L1、L2之间是方向水平向里的匀强磁场,磁感应强度为B,正方形线圈abcd边长为L(L<d),电阻为R,将线圈在磁场上方h高处由静止释放,当cd边进入磁场时恰能做匀速直线运动,则
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/201408241936416785295.jpg)
(1):线框的质量是多少?
(2)从CD边开始进入磁场到线框完全进入到磁场的过程中,线框中产生的热量是多少?
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/201408241936416785295.jpg)
(1):线框的质量是多少?
(2)从CD边开始进入磁场到线框完全进入到磁场的过程中,线框中产生的热量是多少?
(1)
(2)![](http://thumb.1010pic.com/pic2/upload/papers/20140824/201408241936426141130.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/201408241936421151041.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/201408241936426141130.png)
试题分析:(1)CD边进入磁场时,恰好能做匀速直线运动,所以
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824193643301796.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824193644361592.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824193645141606.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/201408241936421151041.png)
(2)过程中产生的热量等于线圈的机械能减小量,故
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/201408241936470131609.png)
点评:基础题,比较简单,做此类型问题关键是把握受力分析,结合匀速信息列式求解
![](http://thumb2018.1010pic.com/images/loading.gif)
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