题目内容
如图所示,有一电子(质量为m,电荷量的绝对值为e),由静止经电压为Uo的加速电场加速后,沿两块水平正对且平行放置的金属板的中线进入板间。已知两块金属板间的距离为d、板间的电压为U,若电子刚好擦着板的边缘射出电场。不计重力,求:
(1)电子射出加速电场时的速率
(2)金属板的长度![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824123335972185.gif)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/201408241233359886192.jpg)
(1)电子射出加速电场时的速率
(2)金属板的长度
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824123335972185.gif)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/201408241233359886192.jpg)
(1)
(2分)
(1分)
(2)
(1分)
(1分)
(1分)
解得
(2分)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824123336003546.gif)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824123336019585.gif)
(2)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824123336050393.gif)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824123336050588.gif)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824123336066488.gif)
解得
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824123336081572.gif)
略
![](http://thumb2018.1010pic.com/images/loading.gif)
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