题目内容
如图所示,为一球形空腔导体(不带电),现将一个带正电的小金属球A放入腔中,当静电平衡时,图中a、b、c三点的场强和电势的关系正确的是 ( )
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/201408250008092302824.jpg)
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/201408250008092302824.jpg)
A.Ea>Eb>Ec,φa>φb>φc | B.Ea>Ec>Eb,φa>φb>φc |
C.Ea=Eb=Ec,φa=φb>φc | D.Ea=Eb>Ec,φa=φb>φc |
B
试题分析:当静电平衡时,空腔环形导体内壁感应出负电荷,外表面感应出正电荷,画出电场线如下图:
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/201408250008092466752.png)
由于a处电场线较密集、c处电场线较稀疏、b处电场强度为零,所以有
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/20140825000809261575.png)
![](http://thumb2018.1010pic.com/images/loading.gif)
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