题目内容
如图所示,实线为电场线,虚线为等势面,相邻两等势面间的电势差相等.一个正电荷在等势面L3处的动能为20 J,运动到等势面L1处时动能为零;现取L2为零电势参考平面,则当此电荷的电势能为4 J时,它的动能为(不计重力及空气阻力)( )
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/201408250007455181985.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/201408250007455181985.png)
A.16 J | B.10 J | C.6 J | D.4 J |
C
试题分析:根据动能定理得知从L3到L1处电场力做的功
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/20140825000745534897.png)
![](http://thumb2018.1010pic.com/images/loading.gif)
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A.16 J | B.10 J | C.6 J | D.4 J |