锦秋A-Level,雅思+A-Level+英国留学!
咨询热线:400-966-9730
留学院校库
官方微信 官方微信
官方微博 官方微博
ALP

首页 >  考试技巧分享 > A-Level物理——电场与电场力备考要点

A-Level物理——电场与电场力备考要点

来源:      浏览:      发布日期:2018-08-02 15:56

返回列表

锦秋A-Level考培+雅思+留学申请一站式服务,专为有志于申请英国G5超级精英大学以及澳洲八大高校的中学生设计。锦秋A-Level设置一站式计划、学霸计划、国际班互补计划三大课程体系,开设数学、进阶数学、物理、化学、生物、经济学、会计学等优势学科,一对一规划学习方案,满足学生不同层次的学习需求;全海归教师授课,助力学生英语高能高分;专业助教团队贴心服务,巩固学习效果,为学生答疑解惑。

为配合大家更好的复习A-Level考试,新东方刘欣梦老师为大家讲解A-Level物理考试电场与电场力Electric Fields and Forces revision复习要点。希望能够对大家的A-Level考试有所帮助。

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

This shows that:

锦秋A-Level拥有经验丰富的老师为学生准确客观评估自身实力,了解学生与要求的差距在哪,再根据学术背景,志愿和能力进行配对,致力于为同学们找到最合适的大学和课程。

推荐阅读

2022年QS世界大学排名(部分院校) more
大学名称 QS排名
A-level考培+雅思+留学申请
爱德思授权考点
助力申请世界大学本科
新航道17年专注于国际化语言教育和留学考培+申请
专职助教+留学服务
专职讲师教学+助教服务

服务热线:400-966-9730

邮箱:alevel@xhd.cn

地址:北京海淀区丹棱街6号丹棱soho九层901