题目内容
(15分)如图所示,半径为r1的圆形区域内有匀强磁场,磁场的磁感应强度大小为B0、方向垂直纸面向里,半径为r2的金属圆环右侧开口处与右侧电路相连,已知圆环电阻为R,电阻R1= R2= R3=R,电容器的电容为C,圆环圆心O与磁场圆心重合。一金属棒MN与金属环接触良好,不计棒与导线的电阻,电键S1处于闭合状态、电键S2处于断开状态。
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/201408241350017729576.png)
(1)若棒MN以速度v0沿环向右匀速滑动,求棒滑过圆环直径的瞬间产生的电动势和流过R1的电流。
(2)撤去棒MN后,闭合电键S2,调节磁场,使磁感应强度B的变化率
,
为常数,求电路稳定时电阻R3在t0时间内产生的焦耳热;
(3)在(2)问情形下,求断开电键S1后流过电阻R2的电量。
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/201408241350017729576.png)
(1)若棒MN以速度v0沿环向右匀速滑动,求棒滑过圆环直径的瞬间产生的电动势和流过R1的电流。
(2)撤去棒MN后,闭合电键S2,调节磁场,使磁感应强度B的变化率
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824135001803712.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824135001850357.png)
(3)在(2)问情形下,求断开电键S1后流过电阻R2的电量。
(1)E=2Br1v0(2)
(3) ![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824135002162912.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/201408241350021151075.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824135002162912.png)
(1)棒MN的电动势E=2Br1v0 (2分)
流过R1电流的大小I1=
,方向为自左向右流过R1(2分)
(2) 电动势
(2分)
电流
(1分)
在
时间内产生的焦耳热
(2分)
(3)电键
闭合时,
=
(2分)
电键
断开后,
(2分)
流过电阻
的电量
(2分)
流过R1电流的大小I1=
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/201408241350021931268.png)
(2) 电动势
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/201408241350023021215.png)
电流
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/201408241350025201185.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824135002552408.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824135002598362.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/201408241350026921550.png)
(3)电键
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824135002754393.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824135002848754.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824135002895820.png)
电键
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824135002754393.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824135002988904.png)
流过电阻
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824135003098413.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/201408241350031601682.png)
![](http://thumb2018.1010pic.com/images/loading.gif)
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