题目内容
如右图所示,AC、BD为圆的两条互相垂直的直径,圆心为O,半径为r,将等电荷量的两正、负点电荷放在圆周上,它们的位置关于AC对称,+q与O点的连线和OC夹角为30°,下列说法正确的是( )
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/201408242201089294052.jpg)
A.A、C两点的电势关系是![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824220108944513.png)
B.B、D两点的电势关系是![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824220109350480.png)
C.O点的场强大小为![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824220109833546.png)
D.O点的场强大小为![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824220110707662.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/201408242201089294052.jpg)
A.A、C两点的电势关系是
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824220108944513.png)
B.B、D两点的电势关系是
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824220109350480.png)
C.O点的场强大小为
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824220109833546.png)
D.O点的场强大小为
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824220110707662.png)
C
试题分析:在等量异种点电荷的电场中,两点电荷连线的中垂面是一个等势面,因此
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824220108944513.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824220112517513.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824220109833546.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824220109833546.png)
故选C
点评:本题关键抓住电场线与等势线的对称性,注意空间每一点的电场是由两个点电荷产生的电场叠加,是考查基础的好题.
![](http://thumb2018.1010pic.com/images/loading.gif)
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