A-Level物理电场与电场力复习要点

　　A-Level物理在考试形式上也和国内物理差别很大。A-Level物理只有单选和大题两种体型，大题里包括了计算题和解释题。计算题一般占的分值并不是特别多，以及大部分都是套用公式的运算，难度不大，不会像国内的题目出的那么难，那么灵活。那么今天小编就给大家整理一下A-Level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 region 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

　　以上就是小编整理的A-Level物理电场与电场力复习要点，作为强调注重培养学生各方面才能而不只是成为进入世界名校敲门砖的A-level课程，在课程开展的过程中，始终都在平衡着考试和学习能力两者的关系，这点在A-level物理中体现的尤为突出。如果想要了解更多A-Level网络课程可以持续关注本网站！