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Thursday, 22 June 2017

What is Nornaml Capacitors ? How dose it work ? How many Type ? - Hindi



What is Capacitors ? How dose it work ? How many Type ?



Capacitors (sometimes known as condensers) are energy-storing devices that are widely used in televisionsradios, and other kinds of electronic equipment. Tune a radio into a station, take a flash photo with a digital camera, or flick the channels on your HDTV and you're making good use of capacitors. The capacitors that drift through the sky are better known as clouds and, though they're absolutely gigantic compared to the capacitors we use in electronics, they store energy in exactly the same way

What is a capacitor? 




Take two electrical conductors (things that let electricity flow through them) and separate them with an insulator (a material that doesn't let electricity flow very well) and you make a capacitor: something that can store electrical energy. Adding electrical energy to a capacitor is called charging; releasing the energy from a capacitor is known as discharging.







A capacitor is a bit like a battery, but it has a different job to do. A battery uses chemicals to store electrical energy and release it very slowly through a circuit; sometimes (in the case of a quartz watch) it can take several years. A capacitor generally releases its energy much more rapidly—often in seconds or less. 

If you're taking a flash photograph, for example, you need your camera to produce a huge burst of light in a fraction of a second. A capacitor attached to the flash gun charges up for a few seconds using energy from your camera's batteries. 

(It takes time to charge a capacitor and that's why you typically have to wait a little while.) Once the capacitor is fully charged, it can release all that energy in an instant through the xenon flash bulb. Zap!



Definition of Capacitance

There are mainly two concepts for defining capacitance. The electrical concept is given below.
Capacitance is said to be the capacitor’s storage potential. In other words, for an existing potential difference  or voltage “V” across the plates, the capacitance is said to be the amount of charge “Q” stored in between the plates.
Capacitance, C = Q/V
Physical concept of capacitance is that capacitance is defined by the physical characteristics of the two plates, such that the capacitance is equal to the ratio between the square area of a plate and the distance between the plates multiplied by the dielectric of the material in between the plates
Capacitance, C = e0e A/d



Farad

The capacitance of a capacitor is measured in units called Farads.
A capacitor is said to have 1 Farad of capacitance when the capacitor can hold 1 amp-second of electrons at 1 volt at a rate of electron flow of 1 coulomb of electrons per second. As 1 Farad is a big value, the capacitors are usually denoted in micro farads.



Basic Capacitor Circuits

1. Capacitor connected to a battery

A Capacitor that is connected to a battery is shown below.

Capacitor connected to battery
A voltage “V” appears across the capacitor, producing a capacitance “C” and a current “I”. The voltage produced by the battery is accepted by the plate that is connected to the negative of the battery. Similarly, the plate on the capacitor that attaches to the positive terminal of the battery loses electrons to the battery. Thus the capacitor begins charging given by the equation
dq = C*dV, where dQ is the small change in charge and dV is the small change in voltage.
Thus the current can be expressed as
I = C*dV/dt.
When the capacitor is fully charged it will have the same voltage as the battery.



2. Capacitor connected in series

Capacitors C1 and C2 connected in series are shown in the figure below.
capacitor series circuit
When the capacitors have a series connection the total voltage “V” from the battery is split into V1 and V2 across the capacitors C1 and C2. The overall charge “Q” will be the charge of the total capacitance.
Voltage V = V1 + V2
As in any series circuit the current I is the same throughout
Therefore total capacitance of the circuit, Ctotal = Q/V = Q/(V1 + V2)
This can be further calculated as 1/Ctotal  = 1/C1  +  1/C2
Thus, for a circuit having “n” number of capacitors in series
1/Ctotal  = 1/C1  +  1/C2 + 1/C3 + …… + 1/Cn



3. Capacitor connected in parallel

As shown in the figure, two capacitorsC1 and C2 are kept in parallel. The voltage across both the capacitors will be the same, “V”. The charge in the capacitor C1 is Q1 and the charge in capacitor C2 is Q2.  Thus we can write the equations as
C1 = Q1/V and C2 = Q2/V.
Total Capacitance, Ctotal = (Q1+Q2)/V = Q1/V  +  Q2/V = C1 + C2
If there are “n” capacitors kept in parallel, then total capacitance can be written as
Ctotal = C1 + C2 + C3 + … + Cn

capacitor parallel circuit




Advantages

  • Since the capacitor can discharge in a fraction of a second, it has a very large advantage. Capacitors are used for appliances which require high speed use like in camera flash and laser techniques.
  • Capacitors are used to remove ripples by removing the peaks and filling in the valleys.
  • A capacitor allows ac voltage to pass through and blocks dc voltage. This has been used in many electronic applications
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