题目内容
如图1所示,半径为
均匀带电圆形平板,单位面积带电量为
,其轴线上任意一点
(坐标为
)的电场强度可以由库仑定律和电场强度的叠加原理求出:
=2![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824152735401447.png)
,方向沿
轴。现考虑单位面积带电量为
的无限大均匀带电平板,从其中间挖去一半径为
的圆板,如图2所示。则圆孔轴线上任意一点
(坐标为
)的电场强度为 ( )
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/201408241527368682672.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/201408241527369465481.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824152734606303.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824152734668288.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824152734808289.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824152735198266.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824152735261318.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824152735401447.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824152735495932.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824152735198266.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824152735854349.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824152735932260.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824152736244333.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824152735198266.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/201408241527368682672.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/201408241527369465481.png)
A.2![]() ![]() ![]() | B.2![]() ![]() ![]() |
C.2![]() ![]() ![]() | D.2![]() ![]() ![]() |
A
试题分析:由题可知单位面积带电量为
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824152735854349.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824152738864456.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824152736244333.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824152735198266.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824152739083692.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824152735932260.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824152736244333.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824152735198266.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/201408241527394261570.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/201408241527395041226.png)
故选A
点评:此题关键是理解题中所给表达式中各物理量的含义,从而得出无限大均匀带电平板的场强的表达式,再由割补法计算任意点的场强。
![](http://thumb2018.1010pic.com/images/loading.gif)
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