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Capacitor | Capacitor in series and Parallel | Complete detail about Capacitor



Capacitor Definition | capacitor symbol | What is Capacitors?

The capacitor is a passive device designed to store electrical energy as a domain of electric field. Capacitors are used extensively in an electronics circuit. 

A capacitor consists of two conducting plates separated by insulating material. The symbolic representation of the capacitor is given below. 

The capacitance of the capacitor depends on the physical size of the capacitor. Generally, there are three factors that affect the capacitance of the capacitor. Which are

  • (a)The surface area of the plate
  • (b)The space between the plate
  • (c)The permittivity of the material

Symbol of Capacitor | Representation of Capacitor In Circuit

There are many ways to represent a capacitor in the electronics circuit. The Most Common ways to represent a Capacitor in electronics Circuits are given below. These representations of Capacitor are according to the behavior of the capacitor in the electronics Circuit.
Capacitor Symbol
Capacitor Symbol

Capacitor equation | Capacitor Equation for Finding Capacitance of Capacitor | Capacitor formula

Capacitors are important electronics components and these components are being used in each and every electronics circuit. 

According to the requirement of the circuit, a specifics value of the capacitor is required so the capacitance value of each and every capacitor is indicated on its outer surface. 

The capacitance value of the capacitors is function of its shape and size and dielectric material used in the circuit. The relation between various parameters and Capacitance of given capacitors is given by 

Capacitance Formula
where
ε=permittivity of the material
A=surface area of the plate
d=space between the plate

Energy Stored Equation of Capacitor

When a voltage source of V volt is connected across the terminal of the capacitor. The source deposits a positive charge q(say) on the plate connected with the positive terminal of the source and a negative charge on the other plate connected to the negative terminal of the source.

 then the capacitor is said to store electric charge. The amount of charge store on the plate is proportional to the applied voltage level of the source. let q be the amount of charge store when V volt is applied across the terminal of the capacitor.
i.e
q =CV
q/V =C= constant and this constant C is called capacitance of the capacitor

store charge = capacitance X Applied voltage

The SI unit of Capacitance is Farad. One farad is defined as a charge of one coulomb is accumulated on the application of one volt.

1 Farad = 9 x 1011esu

One farad is large quantity hence it is generally represented in microfarad, nano farad, and picofarad

One micro farad =10-6 F
one Nano Farad =10-9 F
One pico Farad =10-12 F

Energy Stored In Capacitor| Capacitor energy Storage

In capacitor the plates are separated by insulator hence when DC voltage is applied across the terminal of the capacitor the there is no current flow through the capacitor but electrical energy is stored in the capacitor as a function of the electric field. The stored electric energy is given as

where C =Capacitance of the Capacitor
V = Applied Voltage

Combination of Capacitor| Series Capacitor | Parallel Capacitor|Capacitor in series and parallel

In market fixed valued capacitors are available but sometimes it required some specific value of capacitance but the availability of that required value of the capacitor is not possible. 

In this Condition grouping of the capacitor is required to meet the required value of capacitance. This grouping of the capacitor is called a combination of the capacitor. 

There are two main ways to combine the capacitor and these are (a) Series Combination (b) Parallel Combination of Capacitor.

Series Combination of Capacitor

When one positive terminal of a capacitor is connected to the negative terminal of the second capacitor and the positive terminal of the second with the negative of the third and so on...

In a series Combination of Capacitor, the Voltage difference between any two capacitors is different if their capacitance are different but the current flowing through all the capacitors is the same.
Hence we can say that Series combination is a voltage divider circuit.

then this type of Combination is called a series Combination of Capacitor. The Series Combination of capacitors is shown below in the Circuit diagram.
Series combination of capacitor
Series Combination of Capacitor
As shown above series combination of the capacitor. the equivalent capacitance between terminal A and B is given as 
Series Combination of capacitor Formula

Parallel Combination of Capacitor

When all identical terminals of the two or more than two capacitors are connected to each other then this type of combination of capacitors is called the parallel combination of capacitorsThe parallel Combination of Capacitors is shown below. 
Parallel combination of capacitor
Parallel Combination of Capacitor

In parallel Combination of Capacitor Voltage Difference between all the Connected Capacitors are the same but Current flowing through each capacitor are different iff Capacitance value of all the capacitors are not identical.
Hence we can say that the Parallel Combination of Capacitors is current divider circuit.
The Equivalent Capacitance between terminal A and B is given as 

Parallel Combination formula of Capacitor

Types of capacitor

Capacitors are classified into three types i.e according to its physical shape, according to its working and according to dielectric used.

Types of Capacitor According to its  Physical shape 

(a) Parallel Plate Capacitor
(b) Cylindrical Capacitor
(c) Spherical capacitor

Parallel Plate Capacitor

In a parallel plate capacitor, two rectangular metallic plates are separated by a distance. Out of these two plate one plate is connected to ground and another is isolated from ground and second plate.

 Some Specific type of Insulating material is inserted between two plates to increase the Capacitance of the Capacitor. 

To increase the capacitance of the capacitor some special types of insulating materials are placed between the two plates.

Cylindrical capacitor

The picture of the cylindrical capacitor is given above. In the cylindrical capacitor, two metallic co-axial cylindrical are separated by some distance.

Out of these two metallic co-axial cylinders,the outer cylinder is grounded to the earth and the other is isolated from the grounded cylinder.

 To increase the capacitance of the capacitor some special types of insulating material are inserted between the two plates.

Spherical Capacitor

In Spherical, Two hollow metallic concentric spheres are separated by a small distance. Out of these two hollow metallic spheres, the outer sphere is grounded and the inner sphere is isolated from the grounded sphere.

 The space between the two-sphere is filled by insulating material like mica, paper, etc to increase the capacitance of the capacitor.

Types of Capacitor According to its Working 

According to working, there are three types of capacitor i.e

(a) Fixed Capacitor

This type of capacitor has a fixed capacitance value. the capacitance value of this type of capacitor can not be change by anyway. 

A fixed capacitor is classified according to the type of material used as its dielectrics, such as paper, oil, mica, or electrolyteThese capacitors are used in all types of electrical and electronic circuits.

(b)Adjustable Capacitor

As per the name of the capacitor, the capacitance value of this type of capacitor can be adjusted with the help of a small screwdriver, and this type of capacitor are broadly used in receivers and transmitters.

(c)Variable Capacitor

The capacitance value of the variable capacitor can vary from its upper limit to its lower limit by rotating its shaft and these type capacitors are used in receivers and transmitters.

Types of Capacitor According to its Dielectric Used

There are five types of capacitors according to dielectric material used in capacitor.these are

(a) Paper Capacitor

In a paper capacitor, wax paper is used as an insulating material. these capacitors are normally 2.5 µF and can work on up to 2000 volts Dc supply.

(b) Mica Capacitor

In mica capacitor, thin mica sheets are used as insulating material. These capacitors are normally 0.1µF  and can work on 2500 volt dc supply.

(c) Ceramic Capacitors

In this capacitor ceramic materials are used as insulating material. The capacitance value of these capacitors is 0.2 µF and it can work on 1500 Volt DC Supply.

(d) Electrolytic Capacitors

In this type of capacitors of a layer of ammonium borate, aluminum borate type of material is electroplated on the positively charged aluminum plate of capacitors.these capacitors are normally of 2000µF  and it can work on 450 volt DC supply.

(e) Oil Dielectric Capacitors

In this type of capacitor, minerals oil is used as insulating material. The capacitance value of this type of capacitor are normally of 1µF  and it can work on 25000 Volt DC supply.
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