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两等量同种点电荷在空间的场强分布比较复杂。高中物理课本(必修)第二册仅给了一张电力线图。从这幅图来看至少可以说明两点。(1)两电荷连线的中点及无穷远处场强为零。(2)连线的中垂线上的场强方向沿着中线,并对称分布,中垂线上场强有极大点。这个极点位置到底在哪里呢?现行教科书及教参没有明示。这给教学带来了一些困惑。时而有学生问:“这个极大点是否能用比例尺,从课本上的电力线图测量出来?”我想:“电力线图是人们为描述电场而人为画出来的,如果描绘正确,即电力线的疏密与E的大小成正比,应该是可以找出这个极大点的位置的”。本文就这个问题进行如下探讨。
The field intensity distribution of two equal amounts of the same kind of point charge in space is more complicated. The second volume of high school physics textbook (required) only gave a power line diagram. Judging from this picture, at least two things can be explained. (1) The midpoint of the two-charge connection and the field strength at infinity are zero. (2) The direction of field strength on the perpendicular line of the line is along the midline and symmetrically distributed. The field intensity on the midline is a maximum point. Where exactly is this pole position? The current textbooks and teaching parameters are not expressly stated. This brings some confusion to the teaching. From time to time, some students ask: “Is this maximum point measured from the power line graph in the textbook using a scale?” I thought: “The power line map is drawn by people to describe the electric field. If the depiction is correct, the power line is sparse. The density is proportional to the size of E, and it should be possible to find the location of this great point." This article discusses this issue as follows.