题目内容
(10分)如图所示,质量为m的单匝正方形线圈,其边长为L,在距底边2L的匀强磁场上方由静止开始自由下落,设线圈下落过程中线框平面始终位于纸面内且底边保持水平,当线框的底边刚进入磁场区域时,恰能在匀强磁场中做匀速运动。若磁场的磁感应强度为B,求:
(1)线圈的电阻多大?
(2)线圈进入磁场的过程中单位时间内有多少机械能转化为电能?
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/201408241322068591344.png)
(1)线圈的电阻多大?
(2)线圈进入磁场的过程中单位时间内有多少机械能转化为电能?
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/201408241322068591344.png)
(1)
(2)![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824132206937701.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824132206906978.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824132206937701.png)
(1)
,
,
…………3分
上式联立得:
,………………2分
(2)
,所以
…………5分
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824132206968588.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824132207031592.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824132207078634.png)
上式联立得:
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824132206906978.png)
(2)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824132207327588.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824132206937701.png)
![](http://thumb2018.1010pic.com/images/loading.gif)
练习册系列答案
相关题目