ALevel考试科目众多，ALevel物理就是其中比较常见的科目，很多考生在选课的时候都会选择物理，不过物理考试考察知识面很广，题目难度往往很大，下面我们为大家介绍ALevel物理电场与电场力复习要点！

　　Part 1 Electric Field Shapes 电场概念及表示

　　Electric Field

　　“An electric field is a r egion in which particles with charge experience a force”

　　Field Shape Diagrams

　　We represent electric fields with diagrams that have conventions (or rules) that need to be followed.

　　For example:

　　The field lines (and arrows) show the direction of the force that would be felt by a positive charge at that point in the field. Note that unlike gravitational fields, electric fields can attract or repel objects.

　　The spacing between the lines shows how strong the field is at that point. In this case it’s strongest near to the charge because the lines are closest there.

　　This field is uniform because the spacing between the lines remains the same throughout the field shown. The field lines are parallel and equispaced.

　　Part 2 Electric field strength 电场强度

　　This is defined as the force per unit charge acting at a point in the field. So an equation for it is:

　　Where:

　　E = electric field strength

　　F = force acting in newtons

　　q = the charge in coulombs

　　Units of E: NC-1 or Vm-1 (these are the same thing!!)

　　(1)匀强电场Uniform Fields

　　There is one special example you also need to know :

　　This is a uniform field. The field strength at any point in this field is:

　　where

　　V = the pd between the plates

　　d = the distance separating the plates.

　　Field strength is a vector – it has direction as well as magnitude.

　　This is important to remember because in electric fields you can have field strengths acting in different directions due to different signs of charge.

　　Radial Fields

　　A particularly useful equation to find field strength around a point charge (note – the first pictures is the field diagram section were point charges) is:

　　where

　　Q = the charge causing the field

　　r = the separation between the charge and the point you are considering

　　ε = permittivity (see below for notes).

　　You can also write this as

　　This shows that:

　　以上就是ALevel物理电场与电场力复习要点，希望大家能够好好复习，提高备考能力，并且小编建议大家要好好积累词汇，这样才能顺利通过考试，如果还想了解更多关于alevel真题下载、alevel考试报名的信息，可以在线咨询我们或添加客服微信kewo11！