题目内容
静电透镜是利用静电场使电子束会聚或发散的一种装置.其中某部分静电场的分布如题3图所示,虚线表示这个静电场在纸平面内的一簇等势线,等势线的形状为轴对称图形,等势线的电势沿
轴正向增加,且相邻两等势线的电势差相等.一个电子从
点平行
轴射入电场中,从
点传穿出电场后会聚到
轴上.则
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/201408250029211633286.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/20140825002921100266.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/20140825002921116283.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/20140825002921100266.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/20140825002921131299.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/20140825002921100266.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/201408250029211633286.png)
A.电子沿![]() |
B.电子在![]() ![]() |
C.电子穿过电场的过程中,电场力始终做正功 |
D.电子穿过电场的过程中,电场先做正功后做负功 |
C
试题分析:在
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/20140825002921100266.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/20140825002921100266.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/20140825002921100266.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/20140825002921350562.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/20140825002921365412.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/20140825002921381512.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/20140825002921397581.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/20140825002921116283.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/20140825002921131299.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/20140825002921459700.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/20140825002921365412.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/20140825002921100266.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/20140825002921506527.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/20140825002921537495.png)
![](http://thumb2018.1010pic.com/images/loading.gif)
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