Magnetic Flux
Core Sentence / 核心句
Magnetic flux is the signed scalar measure of magnetic field passing through an oriented surface.
中文理解：磁通量把 在 surface normal 方向上的分量对整个面积累加。
Definition / 定义
uniform flat surface：
是 与 area normal 的夹角。
Unit / 单位
Closed Surface / 闭合曲面
这是 Gauss’s law for magnetism。
Nonuniform Field / 非匀强场
必须 integrate。long wire 旁 rectangular surface：
Watch Out / 易错点
- angle is measured from surface normal。
- flux is scalar, with sign。
- open-surface flux can be nonzero。
- closed-surface net magnetic flux is zero。
- nonuniform field cannot use simple 。