在负电荷产生的电场中的任意一点,正试探电荷所具有的电势能一定大于负试探电荷所具有的电势能 对吗?为什

2025年03月16日 20:48
有2个网友回答
网友(1):

错!
电势能Ep=qφ(电势)
在负电荷产生的电场中各点的电势φ为负值(无限远处电势为0,顺着电场线电势降低)
所以,当q为正时,Ep为负;当q为负时,Ep为正
即:在负电荷产生的电场中的任意一点,正试探电荷所具有的电势能一定小于负试探电荷所具有的电势能

或者这样:
无限远处电势能为0
如将正点荷从该点移到无限远处,电场力做负功,电势能增加.(电场力为引力,故做负功),增加后才为0,当然移动前具有的电势能为负;
如将负点荷从该点移到无限远处,电场力做正功,电势能减小.(电场力为斥力,故做正功),减小后为0,当然移动前具有的电势能为正;

网友(2):

回答这个问题的前提就是点电荷中电势参考点能否任意选择?几乎所有的解答都是以无穷远电势为零作为前提的,这到底是必须的?还是可以任意的呢?我觉得要使这个问题有意义,前提应该是同时存在这两个异种电荷,这样零势面的选择就必须是无穷远或与无穷远等电势的那个等势面.

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