题目内容
如图所示,两个相同的带等量正电的圆环正对放置,电荷均匀分布,O1O2为两圆心的连线,P为O1O2的中点。一质量为m、带电量为-q(q>0)的点电荷以初速度
从O1点沿O1O2方向射出,恰能到达P点.不计重力,点电荷-q克服电场力做的功为W。若将-q换成+q,质量不变,仍以初速度
从O2点沿O2O1方向射出,点电荷+q到达P点时的速度大小为
, 则( )
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/2014082500252121913787.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/20140825002521172322.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/20140825002521172322.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/20140825002521203264.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/2014082500252121913787.png)
A.![]() | B.![]() | C.![]() | D.![]() |
BC
试题分析:由题意可知,O1P的电场强度方向从P到O1,在带正电粒子在两个相同的带等量正电的圆环产生电场中,在电场阻力作用下,根据动能定理可知,电场力做负功导致动能的减小,则有
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/20140825002521297883.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/20140825002521312614.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/20140825002521328926.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/20140825002521343500.png)
![](http://thumb2018.1010pic.com/images/loading.gif)
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