看板Physics
标 题Re: [问题] 点电荷
发信站椰林风情 (Tue Nov 20 23:10:03 2007)
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==> [email protected] (天煞孤星) 提到:
> 有一题高中关於"点电荷"的选择题是这样的：
> A.专指一带电小质点
> B.专指带电之金属球
> C.指带电体间之距离远大於带电体本身
> D.指带电体甚大於两者间之距离
> 答案是C
> 我想问A可以选吗
> 不能选的原因，是因为那个"专"的原因吗？
> thx.
In physics, no such "single point source" exists in the real world.
If you find a positive source somewhere, a corresponding negative
source must exist elsewhere. :>
if you wanna choose the answer "A", the description shall probably
be modified to "a positive point source is located in origin of
the Catesian coordinates, and a negative point source located
in the infinite".
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