题目内容
如图所示,
和
为固定在绝缘水平面上两平行光滑金属导轨,导轨左端
间接有阻值为
=
导线;导轨右端接有与水平轨道相切、半径
内壁光滑的半圆金属轨道。导轨间距
,电阻不计。导轨所在平面
区域内有竖直向上
的匀强磁场。导轨上长度也为
、质量
、电阻
=
的金属棒
以
=
速度进入磁场区域,离开磁场区域后恰好能到达半圆轨道的最高点,运动中金属棒始终与导轨保持良好接触。已知重力加速度
=
。求:
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/201408241649204096023.png)
(1)金属棒
刚滑出磁场右边界
时的速度
的大小;
(2)金属棒滑过磁场区的过程中,导线
中产生的热量
。
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824164915853513.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824164916165399.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824164916555461.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824164916930327.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824164917195403.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824164917554500.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824164917772491.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824164918006506.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824164918240477.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824164918459414.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824164918630623.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824164918849361.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824164919067358.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824164919254396.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824164919644323.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824164919878459.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824164920050273.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824164920221520.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/201408241649204096023.png)
(1)金属棒
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824164919254396.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824164920830367.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824164921079265.png)
(2)金属棒滑过磁场区的过程中,导线
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824164916930327.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824164921454333.png)
(1)
(2)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824164921719506.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824164921906501.png)
试题分析:(1)在轨道的最高点,根据牛顿定律
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824164922125712.png)
金属棒刚滑出磁场到最高点,根据机械能守恒
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824164922281993.png)
由①②式代入数据解得
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824164921719506.png)
(2)对金属棒滑过磁场的过程中,根据能量关系
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824164922655949.png)
对闭合回路,根据热量关系
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824164922873803.png)
由④⑤式并代入数据得
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824164921906501.png)
点评:考查的问题较多,但多为基础知识的应用,掌握好法拉第电磁感应定律、安培力、圆周运动及电路的性质即可顺利求解.
![](http://thumb2018.1010pic.com/images/loading.gif)
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