题目内容
(15分)如图所示,水平放置的平行金属板间有竖直方向的匀强电场,金属板长度和板间距离均为L,金属板左侧有电压为U0的加速电场,一电量为q的带正电粒子从静止开始经加速电场加速后,从金属板中央水平进入匀强电场,恰好通过金属板右侧边缘,不计粒子重力,求:
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/20140825003532475706.png)
(1)金属板间电压U; (2)带电粒子通过金属板右侧边缘时的动能.
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/20140825003532475706.png)
(1)金属板间电压U; (2)带电粒子通过金属板右侧边缘时的动能.
(1)
(2) ![](http://thumb.1010pic.com/pic2/upload/papers/20140825/20140825003532490668.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/20140825003532475502.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/20140825003532490668.png)
试题分析:(1)设粒子质量为m,通过加速电场时速率为v0,有
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/20140825003532521837.png)
以v0进入金属板间,历时t,通过金属板右侧边缘
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/20140825003532537465.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/20140825003532553675.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/20140825003532584697.png)
解得:
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/20140825003532475502.png)
(2)在加速电场中电场力做功
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/20140825003532615658.png)
匀强电场中电场力做功
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/20140825003532631855.png)
带电粒子通过金属板右侧边缘时的动能
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/20140825003532646696.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/20140825003532490668.png)
![](http://thumb2018.1010pic.com/images/loading.gif)
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