题目内容
如图所示为一个负点电荷的电场.A、B是电场中的两点,由图可知
(填“>”、“=”或“<”).若将电荷量为q=5ⅹ10-8C的负电荷置于A点,所受电场力为2ⅹ10-4N,则A点场强大小是 N/c,方向指向 (填“右”或“左”);若将电荷q从A点移走,则该点的电场强度大小是 N/C。![](http://thumb.1010pic.com/pic2/upload/papers/20140824/201408241506439672064.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824150643764388.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824150643889394.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/201408241506439672064.png)
> 2.0×103 左 2.0×103
试题分析:根据公式
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824150644045680.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824150644107535.png)
根据公式
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824150644154559.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/201408241506442631530.png)
电场中一点的电场强度大小和试探电荷无关,所以移走q后,该点的电场强度仍为
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824150644388768.png)
点评:本题最容易出错的地方在于电场中一点的电场强度大小和试探电荷无关,所以移走q后,该点的电场强度不变
![](http://thumb2018.1010pic.com/images/loading.gif)
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