题目内容
如图所示,三个等势面上有a、b、c、d四点,若将一正电荷由c经a移到d点,电场力做正功W1;若由c经b移到d点,电场力做正功W2,则W1与W2,c、d两点电势φc、φd关系为( )
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/201408241453533572179.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/201408241453533572179.png)
A.W1>W2,φc>φd |
B.W1<W2,φc<φd |
C.W1=W2,φc<φd |
D.W1=W2,φc>φd |
D
试题分析:由电场力做功与路径无关可知,W1=W2,AB错;由Wcd=qUcd得到Wcd>0,q>0,所以Ucd>0,Ucd=
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824145353747601.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824145353794530.png)
点评:学生清楚电场力做功与重力做功相似,两个力都是保守力,两个力做功都与路径无关,在用电场力做功的公式和电势差的公式时,注意下角标的顺序要一致
![](http://thumb2018.1010pic.com/images/loading.gif)
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