题目内容
如图甲所示,匀强磁场方向垂直纸面向里,磁场宽度为
,正方形金属框边长为
,每边电阻均为R/4,金属框以速度v的匀速直线穿过磁场区,其平面始终保持与磁感线方向垂直,当金属框cd边到达磁场左边缘时,匀强磁场磁感应强度大小按如图乙所示的规律变化.
(1)求金属框进入磁场阶段,通过回路的电荷量;
(2)在图丙i-t坐标平面上画出金属框穿过磁场区的过程中,金属框内感应电流i随时间t的变化图线(取逆时针方向为电流正方向);
(3)求金属框穿过磁场区的过程中cd边克服安培力做的功W.![](http://thumb.1010pic.com/pic2/upload/papers/20140824/201408241211056181755.gif)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/201408241211056343750.gif)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824121105571215.gif)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824121105587198.gif)
(1)求金属框进入磁场阶段,通过回路的电荷量;
(2)在图丙i-t坐标平面上画出金属框穿过磁场区的过程中,金属框内感应电流i随时间t的变化图线(取逆时针方向为电流正方向);
(3)求金属框穿过磁场区的过程中cd边克服安培力做的功W.
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/201408241211056181755.gif)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/201408241211056343750.gif)
(1)
(2)
(3)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824121105680616.gif)
(2)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/201408241211056962302.gif)
(3)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824121105712759.gif)
(1)金属框进入磁场阶段产生的电动势
(2分)
产生逆时针方向的感应电流
(1分)
则通过回路的电荷量
(2分)
(2)金属框在磁场中产生逆时针方向的感应电流![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824121105774737.gif)
金属框离开磁场阶段产生的顺时针方向的感应电流![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824121105790540.gif)
金属框内感应电流的i-t图线如图所示. (5分)
(3)线圈进入磁场时,cd边克服安培力做的功
(1分)
线圈在磁场内运动时,cd边克服安培力做功的功率
,其中
(1分)
此过程克服安培力做的功
(1分)
则
(1分)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824121105727441.gif)
产生逆时针方向的感应电流
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824121105743318.gif)
则通过回路的电荷量
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824121105680616.gif)
(2)金属框在磁场中产生逆时针方向的感应电流
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824121105774737.gif)
金属框离开磁场阶段产生的顺时针方向的感应电流
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824121105790540.gif)
金属框内感应电流的i-t图线如图所示. (5分)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/201408241211056962302.gif)
(3)线圈进入磁场时,cd边克服安培力做的功
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824121105836795.gif)
线圈在磁场内运动时,cd边克服安培力做功的功率
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/201408241211058361020.gif)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824121105868616.gif)
此过程克服安培力做的功
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/201408241211058831027.gif)
则
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824121105712759.gif)
![](http://thumb2018.1010pic.com/images/loading.gif)
练习册系列答案
相关题目