在ALevel物理學(xué)習(xí)中，電場與電場力部分是考試中必考的一點(diǎn)，卻也是很多同學(xué)們比較難理解的部分。今天A加未來小編就帶大家相信解讀一下這部分所設(shè)涉及到的ALevel物理考點(diǎn)內(nèi)容，來幫助同學(xué)們加深這部分印象。
Part 1 Electric Field Shapes電場概念及表示
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電場強(qiáng)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)勻強(qiáng)電場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加未來小編關(guān)于電場與電場力部分ALevel物理考點(diǎn)的解讀，同學(xué)們可以作為在這部分復(fù)習(xí)中的參考。如果對于ALevel物理課程學(xué)習(xí)還有哪些不明白的，一定要及時反饋給A加未來國際課程老師，讓老師一對一為你進(jìn)行專項的課程輔導(dǎo)吧！
