【文魁大脑】《博赞思维导图管理师认证班》】陈木子 第三幅 《15 Electric Fields 读书笔记》

图片发自App

【姓名】陈木子

【导师】袁文魁、王玉印

【导图解说】

      这是第三幅，以读书笔记为题，读的书就是我们物理课本第15单元。中心图是一朵乌云正在打雷和下雨，乌云后面藏着太阳（这纯属夺人眼球）以及两个电荷（+和-，用来说明这幅导图关于物理）

Main Branch 1: Laws of electrostatics. There are only two kinds of electric charges, namely positive change and negative charge. Their interactions: Like charges repel; unlike charges attract. Formula to determine the electric force between two point charges q1 and q2, distance r apart in free space or air: F=q1q2/4πε0r^2, where ε0 is the permittivity of the free space and its value is 8.85*10*-12•C^2•N^-1•m^-2. When a charged body is held near an uncharged conductor, some electrons in the conductor will move towards the charged body. Thus the charges are unlike and the body attracts the conductor.

Main Branch 2: Principles of electrostatics. Materials are categorized into two categories, which are conductors and insulators. Conductors are materials that have free charge carriers and insulators do not have free charge carriers. Each atom has negatively charged electrons around a nucleus which includes positively charged protons. When an atom is ionized, it either loses electrons and becomes positive or gains electrons and becomes negative. Charge is conserved and cannot be created or destroyed. A body can be charged by friction, induction or contact. There are a few electrostatic hazards. E.g. lightning and fires.

Main Branch 3: Application of electrostatics. Electrostatics can be applied in various ways, e.g. photocopiers, spray printing and precipitator.

Main Branch 4: Electric field. An electrically charged body sets up an electric field in the space around it. The direction of the field at a given point is the direction of the force that acts on a positive test charge placed at a point. Electric field patterns: Isolated positive point charge: the field lines are directed away from the positive charge. Isolated negative point charge: the field lines are directed towards the negative charge. Between two isolated opposite point charges: the field lines point away from the positive charge and towards the negative charge. Between two isolated point charges: the field lines from both charges are directed away from each other. Between parallel uniformly charged plates: the field is uniform and the field lines point away from the positive charge and towards the negative charge.