The estimation of the electric field in simple situations provides an opportunity to develop intuition about the models used in physics. We propose an activity aimed at university students where the electric field of a finite line of charge is compared, analytically or numerically, with the fields of an infinite line and of a point charge. Contrary to intuition, it is not necessary to get very close for the line charge to be considered infinite, nor to move very far away for the finite line field to resemble that of a point charge. We conducted this activity with a group of students and found that many of them have not yet developed an adequate intuition about the approximations used in electromagnetism.

在简单情况下对电场的估计提供了一个机会，可以培养对物理学中使用的模型的直觉。我们提出了一项针对大学生的活动，在该活动中，将有限电荷线的电场与无限线和点电荷的场进行分析或数值比较。与直觉相反，没有必要非常接近线电荷被认为是无限的，也没有必要移动很远才能使有限线场类似于点电荷的线场。我们与一群学生一起进行了这项活动，发现他们中的许多人还没有对电磁学中使用的近似值产生足够的直觉。