A Capacitor is a two terminal passive device used to store energy in the form of electric charge. It is comprised of two parallel plates which are separated from each other either by air or by some other insulating device like paper, mica, ceramic etc.
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Capacitance of a Capacitor
The Capacitor is made up of two conductors separated by an insulator also known as dielectric. The dielectric can be of different types, you can use any of the dielectric material between the plates of the capacitor as per your need.
The amount of electrical energy stored in the capacitor is known as its capacitance. The Capacitance of a capacitor is directly proportional to the capacity of the capacitor for storing charge.
For example; the bigger the tank the more water it can store similarly the bigger the capacitance, the more charge it can store.
How to Increase Capacitance
The capacitance of the capacitor can be increased by following three ways :
- By increasing the size of the plates, that means Capacitance is directly proportional to the plate size of the capacitor
- By decreasing the distance between the plates
- Make dielectric as good as an insulator.
Symbol of a Capacitor consists of two parallel lines separated from each other i.e. Flat, curved or an arrow passes through it. The flat line indicates that the capacitor is non-polarized, the curved line indicates that the capacitor is polarized and arrow type indicates that it is of a variable type.
A Capacitor is represented by 2 parallel lines that denotes the parallel plates of a capacitor and Anode and Cathode Points to both sides of the lines. Its Unit is Farad (F).
Capacitance of capacitor is measured in Farads symbolized as F. It is defined as being that a capacitor has the capacitance of one Farad when one coulomb of electric charge is stored in the conductor on the application of one volt potential difference. It has no negative units, it is always positive. The charge stored in a capacitor is given by:
Q = CV
Where Q : charge stored by the capacitor
C : Capacitance value of the capacitor
V : Voltage applied across the capacitor
We can connect capacitor either in series or in parallel as per requirement, one thing is to remember is that the formula is different for calculation in series or parallel.
If we connected capacitor in series then the capacitance formula is:
1/Cs = 1/C1 + 1/C2 + 1/C3 +… + 1/Cn
If we connected capacitor in parallel then the capacitance formula is:
Cp = C1 + C2 + C3 +… + Cn
Capacitor Markings Explanation
Capacitors are marked in different ways depending on its color code, voltage code, Tolerance code and temperature coefficient etc. Here we explain you meaning and values of all such codes marked on different types of capacitors.
(i) Color code: Different schemes are used for different types of capacitors. Nowadays this type of capacitor marking is using less these days but it is available on some older components.
(ii) Tolerance code: Some capacitors have tolerance code depends upon its dielectric material. Following tolerance rating is given below.
Capacitor Tolerance Code and Capacitance Values
|Alphalet on Capacitor||Capacitor Tolerance|
(iii) Temperature coefficient codes: On several capacitors marking or code indicates the temperature coefficient of the capacitor. All these codes are standardized by EIA (Electronics Industries Alliance), these codes are typically used for ceramic and film type capacitors.
Capacitor Temperature Coefficient codes
|Electronic Industries Alliance (EIA)||Industry||Temperature Coefficents|
(iv) Capacitor working voltage codes: Working voltage is the key parameter of any electronic component. Sometimes capacitors are of smaller size and it is not possible to write whole code over it, so for this purpose we write only one character over it which designates specific voltage values. Below we are providing a table which indicates the specific voltage values of the capacitor.
Capacitor Working Voltage Codes
|Letter||Voltage||EIA capacitor voltage codes|
|e||2.5||0e = 2.5VDC|
|G||4||0G = 4.0VDC|
|J||63||0J = 6.3VDC , 1J = 63VDC|
|A||10||1A = 10VDC, 2A = 100VDC|
|C||16||1C = 16VDC, 2C= 160VDC|
|D||20||2D = 200VDC|
|E||25||1E = 25VDC , 2E = 250VDC|
|V||35||2V = 350VDC|
|H||50||1H = 50VDC|
(v) Number code: Most capacitors have a number printed on their body indicates their electrical properties. Capacitors like electrolytic are larger in size usually display the actual capacitance together with the unit like 120 µF while capacitors like ceramic are smaller in size use short notations of three numeric digit and letter where digit indicates the capacitance value in pF and letter indicates tolerance. For example, let’s consider text 343M 220V available on the body of the capacitor. It designates 34 x 103 pF = 34 nF (±20%) with the working voltage of 220V. To prevent the risk of breaking down the dielectric layer always use highest working voltage.
Applications of capacitors:
Capacitors are widely used in the electronic industries. Following of its application are:
- It is used in coupling of two stages of a circuit.
- Used in filter networks.
- Used for smoothing the output of the power supply circuits.
- Used for delay application like in 555 timer IC controlling the charging and discharging.
- It is used for Phase alteration.
- In camera flash circuits, it stores charges.
Before you Go..
Capacitor is one of the most used passive component. But if you look closely in any circuit, you will find other components too like resistance, transistors, op-amps etc. So, we have another excellent guide on electrical symbols you will mostly encounter with. Read On now
Iam sam, I would like to know the difference between audio purpose and general purpose capacitors which have the same values.