# How does a capacitor work 2022 | Capacitor Formula

## What Is Capacitor Work

### What Is Capacitor?

A Capac­i­tor is a charg­ing and dis­charg­ing the ener­gy much faster device stored a elec­tric charge. it’s a lit­tle bit like a bat­tery except it stores ener­gy in dif­fer­ent way. It can­not store as much ener­gy as a bat­tery. This is very use­ful and that’s why you will find capac­i­tors used in almost every cir­cuit board

### Capacitor Formula

C = Q÷V

C = Capacitance

Q = Charged stored in capacitor

V = Volt­age across capacitor

### Unit of Capacitor

Capac­i­tor unit named as Michael fara­day great­est sci­en­tist in history

Capac­i­tor unit is C → FARAD

## How does a capacitor work

• The capac­i­tor is the essen­tial com­po­nent of any­cir­cuit design and in fact, after the resis­tor, it is the sec­ond most used pas­sive com­po­nent in the circuits.
• Now, these capac­i­tors are avail­able in var­i­ous size and shapes.But the basic func­tion of any capac­i­tor is to store the elec­tri­cal energy.So, now in this arti­cle, let’s under­stand how does this capac­i­tor work and how the ener­gy is stored across this capacitor.
• Now, this capac­i­tor con­sists of two con­duc­tive plates which are sep­a­rat­ed by a dielec­tric material.
• Now, this dielec­tric mate­r­i­al is the insu­lat­ing mate­r­i­al and it oppos­es the flow of current.
• So, now let’s under­stand when we apply the volt­age to this capac­i­tor then how the ener­gy is stored across this capacitor.
• Now, before the appli­ca­tion of volt­age, the two con­duct­ing plates of this capac­i­tor are elec­tri­cal­ly neutral.It means that it has the equal amount of pos­i­tive as well as the neg­a­tive charge.
• But once the volt­age is applied to this capac­i­tor, then from the top plate the elec­trons or the neg­a­tive charge is attract­ed towards the pos­i­tive ter­mi­nal of this battery.
• And through the neg­a­tive ter­mi­nal of the bat­tery, the elec­trons are pushed towards the bot­tom plate of this capacitor.
• Now, because of the dielec­tric mate­r­i­al between the two plates elec­trons which are col­lect­ed by at the bot­tom plate of this capac­i­tor are not able to cross this barrier.
• And because of that, you will observe that over the peri­od of time the elec­trons will get accu­mu­lat­ed at the bot­tom plate of this capacitor.
• So, over the peri­od of time, the top plate will have a short­age of elec­trons, while the bot­tom plate will have exces­sive elec­trons Or we can say that the top plate will get pos­i­tive­ly charged
• while the bot­tom plate will get neg­a­tive­ly charged. And because of the charged par­ti­cles, the poten­tial dif­fer­ence will get devel­oped across the two plates.
• Now, the build­ing of charges across the two plates will con­tin­ue till the point the poten­tial dif­fer­ence that is devel­oped across the two plates is equal to the sup­plied voltage.
• Now, because of this poten­tial dif­fer­ence, the elec­tric field will get devel­oped across the two plates.And this devel­oped elec­tric field is direct­ly pro­por­tion­al to the poten­tial dif­fer­ence and it is inverse­ly pro­por­tion­al to the dis­tance between the two plates.
• So, small­er the dis­tance between the two plates, the stronger will be the elec­tric field.
• So, in this way, when we apply the volt­age to the capac­i­tor, then the charges are devel­oped across the two plates of this capac­i­tor and because of the devel­op­ment of the charge,the elec­tric field is devel­oped between the two plates.
• So, in this way, the capac­i­tor stores the ener­gy in form of this elec­tric field Now even if we remove this volt­age source, then also the charges that are devel­oped across the two plates will remain as it is.
• So, unless we apply the con­duc­tive path to this capac­i­tor, the charges that are devel­oped across the two plates will remain as it is.
• So, as you can see over here, the con­duc­tive path is con­nect­ed between the two ter­mi­nals of this capacitor.And load in the form of the bulb is con­nect­ed to this con­duc­tive path.
• So, now when­ev­er we turn on this switch at that time, the elec­trons from the bot­tom plate will get attract­ed towards the top plate.
• And in this way, you will see the trans­fer of charge or flow of cur­rent through this con­duc­tive path. So, now because of the flow of cur­rent, you will see that the bulb will grow.
• And in this way, the cur­rent will flow through this con­duc­tive path and this pro­ce­dure will con­tin­ue till both the plates will become elec­tri­cal­ly neutral.
• So, over the peri­od of time, you will observe that both plates will become elec­tri­cal­ly neutral.And there will not be any flow of elec­trons through this con­duc­tive path.
• And because of that, the bulb will again turn off.So, in this way, the charge that was devel­oped across the capac­i­tor has been dis­charged through this con­duc­tive path.And this phe­nom­e­non can be known as the dis­charg­ing of the capacitor.
• Now, the abil­i­ty of the capac­i­tor to store the charge is known as the capacitance.And it is rep­re­sent­ed as the charge that is devel­oped across the capac­i­tor per unit voltage.
• And gen­er­al­ly, it is denot­ed by the unit of Farad.Now, this farad is a very big unit and usu­al­ly, it is not used to define the capacitance.Rather very small units like mF, uF and pF are used to define the capacitance.
• So, now for the giv­en capac­i­tance if you want to store the more charge across the capac­i­tor then you need to apply the more volt­age across that capac­i­tor Or for the giv­en volt­age sup­pose if you want to store the more charge across the capacitor
• Then you need to select the capac­i­tor in a such a way that it has a large capacitance.So, as you can see over here, by chang­ing the applied volt­age we change the amount of charge that is stored across the capacitor.
• But here we can not increase the volt­age indefinitely.So, for every capac­i­tor, you will find that the max­i­mum volt­age rat­ing has been defined.
• So, the volt­age that is applied across the capac­i­tor should be less than that max­i­mum rating.So, if the applied volt­age is greater than the max­i­mum rat­ed volt­age, in that case, youb­will see the dielec­tric break­down in the capacitor.
• So now let’s see the fac­tors which affect the capac­i­tance of this capac­i­tor. So, there are three fac­tors which affect the capac­i­tance of this capacitor.
• The first is the area of the plates. then the sec­ond fac­tor is the dis­tance between the two plates of this capac­i­tor and the third fac­tor is the per­mit­tiv­i­ty of the dielec­tric material.
• And the rela­tion between three can be giv­en by this expression.That is C is equal to ε*A/d.So, as you can see over here, the capac­i­tance of this capac­i­tor is direct­ly pro­por­tion­al to the area of the plate as well as the per­mit­tiv­i­ty of this dielec­tric material.
• And it is inverse­ly pro­por­tion­al to the dis­tance between the plates.So, now let’s see, how these fac­tors can affect the capac­i­tance of this capacitor.
• So, the first fac­tor is the area of these plates.So, as the area of the plates increas­es, the amount of charge that can be stored across­the plates will also increase.
• And in a way, we can say that the capac­i­tance of the capac­i­tor will increase.Now, the sec­ond fac­tor which affects the capac­i­tance is the dis­tance between the two plates.
• So, now as the dis­tance between the two plates reduces, the elec­tric field that is devel­oped across the two plates will also increase.
• Because it is inverse­ly pro­por­tion­al to the elec­tric field and as this elec­tric field increas­es, the charge that can be stored across the capac­i­tor will also increase.
• So, the third fac­tor which affects the capac­i­tance is the per­mit­tiv­i­ty of the dielec­tric material.Now, this per­mit­tiv­i­ty can be defined as the prod­uct of absolute per­mit­tiv­i­ty and the rel­a­tive permittivity.
• Where this rel­a­tive per­mit­tiv­i­ty is also known as the dielec­tric con­stant of the material.So, because of this dielec­tric mate­r­i­al, the capac­i­tance of the capac­i­tor will increase.
• So, now let’s under­stand how this dielec­tric mate­r­i­al affects the capac­i­tance of the capacitor.Now, like I said before, this dielec­tric mate­r­i­al is the insu­lat­ing material.So, it will not allow the flow of current.
• But this dielec­tric mate­r­i­al has polar molecules.It means that when­ev­er there is no elec­tric field, in that case, these mol­e­cules are aligned randomly.
• But when­ev­er the exter­nal elec­tric field is applied, in that case, these mol­e­cules aligned them­selves accord­ing to the elec­tric field.
• So, at the top edge of the dielec­tric mate­r­i­al, if you see, you will find the neg­a­tive charges.While at the bot­tom end of this dielec­tric mate­r­i­al you will find the pos­i­tive charges.
• Now, these charges devel­op its own elec­tric field, which oppos­es the elec­tric field that is gen­er­at­ed by the capacitor.
• So, because of this dielec­tric mate­r­i­al, the effec­tive elec­tric field of the capac­i­tor will reduce and in a way, we can say that the poten­tial dif­fer­ence that is gen­er­at­ed across the two plates will also reduce, pro­vid­ed the charges that are devel­oped across the two plates are constant.
• So, in that case, to increase the poten­tial we require the more amount of charge across the two plates.So, in a way, we can say that, because of the intro­duc­tion of this dielec­tric material,the capac­i­tor can more amount of charge Or we can say that the capac­i­tance of the capac­i­tor will increase.
• So, these are the three fac­tors which affect the capac­i­tance of this capacitor.