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.
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| 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
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.
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.
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| Series Combination of Capacitor |
As shown above series combination of the capacitor. the equivalent capacitance between terminal A and B is given as
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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 capacitors. The parallel Combination of Capacitors is shown below.
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| 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
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.
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.
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.
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 electrolyte. These capacitors are used in all types of electrical and electronic circuits.
A fixed capacitor is classified according to the type of material used as its dielectrics, such as paper, oil, mica, or electrolyte. These 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.
