题目内容
边长为L、总电阻为R、匝数为n的正方形线框,垂直磁场放在磁感应强度为B的匀强磁场中,t=0时,线框绕OO′轴以周期T匀速转动,如图所示.求:
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/201408241206350362906.jpg)
(1)线框转过30°的过程中,通过线框的电荷量;
(2)从t=0开始转过180°的过程中,通过线框的电荷量.
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/201408241206350362906.jpg)
(1)线框转过30°的过程中,通过线框的电荷量;
(2)从t=0开始转过180°的过程中,通过线框的电荷量.
(1)nBL2(2-
)/2R (2)2nBL2/R
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824120635051225.gif)
(1)线框平面转过30°的过程中磁通量的变化ΔΦ=BS-BS·cos30°=![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824120635051575.gif)
该过程中的平均电动势及平均电流分别为
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824120635082660.gif)
通过线框的电荷量为Q=
·Δt=
=
.
(2)从t=0转过180°的过程中,线框中磁通量的变化为ΔΦ=2BL2,该过程中的平均电动势和平均电流分别为
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824120635223652.gif)
通过线框的电荷量为
.
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824120635051575.gif)
该过程中的平均电动势及平均电流分别为
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824120635067523.gif)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824120635082660.gif)
通过线框的电荷量为Q=
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824120635145192.gif)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824120635176437.gif)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824120635192600.gif)
(2)从t=0转过180°的过程中,线框中磁通量的变化为ΔΦ=2BL2,该过程中的平均电动势和平均电流分别为
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824120635207725.gif)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824120635223652.gif)
通过线框的电荷量为
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824120635238640.gif)
![](http://thumb2018.1010pic.com/images/loading.gif)
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