WAZIPOINT Engineering Science & Technology: Why Capacitor and Capacitance are Used Electrical and Electronic Circuit?

Wednesday, March 27, 2019

Why Capacitor and Capacitance are Used Electrical and Electronic Circuit?

The Purpose of Capacitors Using in Electrical Circuit.


Capacitor is an electrical or electronic device that used to store an electric charge, consisting of one or more pairs of conductors separated by an insulator is known as capacitor.

How Many Types of Capacitor Possible?
Fig- Different Types of Capacitor
Simply we can define, single or multiple conductors or metallic parts when placed in parallel then it form a capacitor.


The effect or action of capacitance, or the behavior of capacitance is known as capacitance.

By definition of capacitance we can say, a capacitor is a passive two-terminal electronic component that stores electrical energy in an electric field and the effect of a capacitor is known as capacitance. 

The basic formula to calculate the capacitance of parallel plate capacitor is as below:

Equation of Parallel Plate Capacitance Measurement

What is Different Types of Capacitors & Their Characteristics?

The most common kinds of capacitors as per named using dielectric materials and/or anode or cathode are: 

Ceramic capacitors have a ceramic dielectric; Film and paper capacitors are named for their dielectrics; Aluminum, tantalum and niobium electrolytic capacitors are named after the material used as the anode and the construction of the cathode (electrolyte).

Ceramic capacitor:
Ceramic CapacitorThe Ceramic Capacitor is named as uses a ceramic material as the dielectric for capacitor which is a fixed-value capacitor where the ceramic material acts as the dielectric.. In Electronic Engineering, the Ceramic capacitors are the most widely used capacitors in the electronic circuits. These capacitors are mainly used where Ceramics were one of the first materials to be used in the proudhon of capacitors.

Electrolytic capacitor: 

Electrolytic capacitor
An electrolytic capacitor is a type of capacitor that uses an electrolyte to achieve a larger capacitance than other capacitor types. An electrolyte is a liquid or gel containing a high concentration of ions. 

An electrolytic capacitor in short named e-cap which is a polarized capacitor whose anode or positive plate is made of a metal that forms an insulating oxide layer through anodization. This oxide layer acts as the dielectric of the capacitor.

Metallized film Capacitor

Metallized film Capacitor: 

Metallized plastic film capacitors come in a variety of forms, using different materials. They are useful in many applications, especially as leaded components. Film capacitors are those kind of capacitors which use a thin plastic film as the dielectric. This film is especially made extremely thin using a sophisticated film drawing process.

Axial Leaded Film foil Capacitor: 

Film foil Capacitor

Type WPP axial-leaded, polypropylene flm/foil capacitors incorporate non-inductive extended foil construction with epoxy end seals. Type WPP is rated for continuous-duty operation over the temperature range of –55 ºC to 105 ºC without voltage derating. Low ESR, low dissipation factor and the inherent stability make Type WPP ideal for tight tolerance, pulse and high frequency applications. 


Tantalum Capacitor:

Tantalum Capacitor

A tantalum electrolytic capacitor is an electrolytic capacitor, a passive component of electronic circuits. It consists of a pellet of tantalum metal as an anode, covered by an insulating oxide layer that forms the dielectric, surrounded by liquid or solid electrolyte as a cathode.

Silver Mica Capacitor:

Silver Mica Capacitor

The silver mica capacitor provides close tolerance values with low levels of value change with temperature. Silver mica capacitors are high precision, stable and reliable capacitors

The silver mica capacitor provides close tolerance values with low levels of value change with temperature and are available in small values, and are mostly used at high frequencies

Super-capacitors or in short SuparCap is made with graphene as the conducting plate are capable of storing a charge similar to lithium-ion batteries.

Amazing Facts About Capacitor and Capacitance

  1. A capacitor is an electrical or electronic circuit component that made of two conducting plates separated by a dielectric or non-conducting insulator material;
  2. Capacitor shapes are fixed, either flat or cylinder;
  3. The Leyden jar was the first capacitor created, invented in 1745 by Pieter van Musschenbroek;
  4. The characteristics of a capacitor is also known as capacitance measured in unit farad;
  5. A capacitor’s conducting surfaces are made of a thin film of conductive metal or aluminum foil;
  6. The positively charged plate is known as the anode and the negatively charged plate is known as the cathode;
  7. To get higher capacitance values dielectric materials should be higher dielectric constant;
  8. The example of dielectric materials used in capacitors are ceramic, air, vacuum, paper impregnated with oil or wax, mylar, polystyrene, mica, glass etc.;
  9. When a capacitor is connected to a power source, positive charges transfer to one of the conducting surfaces, and negative charges are transferred to the other conducting surface;
  10. Normally a capacitor can absorb energy from a circuit and store it temporarily and then return the energy to the circuit;
  11. Capacitor can store the energy for long time that used as data memory circuit in computer technology;
  12. Capacitors discharge very slowly, but many can store a charge for years;
  13. Handling a larger size charged capacitor in the wrong way can result in burns or even death;
  14. A capacitor is discharged slowly when a resistor is connected to each leg of capacitor;
  15. Capacitors are measured in a unit named farad after the scientist Michael Faraday; 
  16. Super-capacitors made with graphene as the conducting plate are capable of storing a charge similar to lithium-ion batteries.

What is the Largest Capacitor in the World?

The Sunvault Energ company collaboration with Edison Power is developing graphene-based super-capacitor technology for use in solar cell arrays. In November 2015 Sunvault announced that announced the creation of the world's largest 10,000 Farad Graphene Supercapacitor. The companies declared that this development is the most significant breakthrough in the development of Graphene Super-capacitors till to date. 

Capacitor Formula:

The formula of capacitor means the total capacitance of a capacitor measured by it's place area and current relations that defined early.
Now, we will find the resultant capacitance when multiple capacitor connect in series or parallel:

Capacitor in Parallel Parallel Capacitor Connection

Capacitor in Series
Capacitor in Series Connection

What is a Capacitor Used for? How is a Capacitor Used in a Motor Circuit?

A run capacitors primary function is to bring the start winding in phase with the run winding. It also adds 30-40 percent more starting torque. But the starting torque is its secondary purpose. Also, the voltage rating of the capacitor- 370 or 440, is the amount of cemf,(counter electromotive force) produced by the windings, magnets, armature, etc of the motor, that the capacitor can handle. 

If a motor produces a back voltage over 370, you must use a 440 rated capacitor. If not, the capacitor will fail. Phase problems occur when a capacitor is either weak or too large for the motor. If a  motor calls for a 7.5 mfd capacitor and the capacitor is weak, the motor will often still start but the capacitor will not be able to bring the star.

Capacitor Working Principle

The capacitance depends on the geometry of the conductors and nature of the medium. A capacitor is a device for storing electric charges. 
Capacitor Working Principle

Consider an insulated conductor (Plate A) with a positive charge ‘q’ having potential V (Fig-a). The capacitance of A is C = q/V.

When another insulated metal plate B is brought near A, negative charges are induced on the side of B near A. An equal amount of positive charge is induced on the other side of B (Fig-b). 

The negative charge in B decreases the potential of A. The positive charge in B increases the potential of A. But the negative charge on B is nearer to A than the positive charge on B. So the net effect is that, the potential of A decreases. Thus the capacitance of A is 

If the plate B is earthed, positive charges get neutralized (Fig-c). Then the potential of A decreases further. 

Thus the capacitance of A is considerably increased. The capacitance depends on the geometry of the conductors and nature of the medium. A capacitor is a device for storing electric charges.


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