题目内容
如图所示,一个圆形线圈的匝数n=1000,线圈面积S=200
,线圈的电阻为r=1Ω,在线圈外接一个阻值R=4Ω的电阻,电阻的一端b跟地相接,把线圈放入一个方向垂直线圈平面的匀强磁场中,磁感应强度随时间变化规律如图线B-t所示.求:
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/201408241159230711943.gif)
(1)从计时起t=3s,t=5s时穿过线圈的磁通量是多少?
(2)a点的最高电势和最低电势各多少?
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824115923040975.gif)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/201408241159230711943.gif)
(1)从计时起t=3s,t=5s时穿过线圈的磁通量是多少?
(2)a点的最高电势和最低电势各多少?
(1)4.0wb (2)-0.8V , 3.2V
:(1)当t=3s时,由图可知
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824115923086953.gif)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824115923086974.gif)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824115923118958.gif)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824115923086974.gif)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824115923149976.gif)
当t=5s时,
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824115923180958.gif)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824115923086974.gif)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824115923211961.gif)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824115923086974.gif)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824115923149976.gif)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824115923274969.gif)
(2)在0s~4s时,产生的感应电动势:
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/201408241159233201290.gif)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/201408241159233361410.gif)
电流由b→a,此时,a点的电势最低,为:
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/201408241159233831149.gif)
在4s~6s时,产生的感应电动势:
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/201408241159234141294.gif)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/201408241159234451411.gif)
电流由a→b,此时,a点的电势最高,为:
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/201408241159234761111.gif)
![](http://thumb2018.1010pic.com/images/loading.gif)
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