课程名称︰普通物理学甲下
课程性质︰数学系大一必带
课程教师︰黄晖理
开课学院：理学院
开课系所︰数学系
考试日期（年月日）︰2014/04/15
考试时限（分钟）：120
试题 :
1. A small circular hole of radius R has been cut in the middle of an infinite,
flat, non-conducting surface that has uniform charge density σ. A Z axis,
with its origin at the hole's center, is perpendicular to the surface. In
unitvector notation, what is the electric field at point P at height z?
https://i.imgur.com/2UyDscK.png
\begin{tikzpicture}
\filldraw[gray] (4.5, 1.5)