ALevel物理考点：电场与电场力内容解析

 

　　在ALevel物理学习中，电场与电场力部分是考试中必考的一点，却也是很多同学们比较难理解的部分。今天A加未来小编就带大家相信解读一下这部分所设涉及到的ALevel物理考点内容，来帮助同学们加深这部分印象。

　　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).

　　以上就是A加未来小编关于电场与电场力部分ALevel物理考点的解读，同学们可以作为在这部分复习中的参考。如果对于ALevel物理课程学习还有哪些不明白的，一定要及时反馈给A加未来国际课程老师，让老师一对一为你进行专项的课程辅导吧！