5,237  members and growing...
  • pic1
  • pic2
  • pic3
  • pic4
  • pic4
  • pic4
  • pic4
  • pic4
Title: Things you may like to know about Capacitors
Capacitor is one of the most essential elements of any Electronics circuit. There are many types of capacitors according to function, construction, material and application. This article is an attempt to cover these briefly, since a book can be written on each type.
Company/Industry Name: Vasudha IT Solutions Pvt. Ltd.
Auother Name: ene@enefinder.com


Capacitor is a 2-terminal passive electronic component that stores energy in form of electric charge 

 similar to a storage battery.  A capacitor is a pair of two conductors separated by a non-conductive region.   The non-conductive region can either be a vacuum or an electrically insulating material (known as a dielectric), like glass, air, paper, plastic, ceramic. [Remember a burger sandwich with layer of vegetables or meat or cheese docked between bread slices?]  Due to this insulating layer, DC current cannot flow through the capacitor, and voltage is present across the plates in the form of an electrical charge.  Every capacitor has Voltage as one of the rating parameters.

 Working Principle 

When there is a potential difference across the conductors (e.g., when a capacitor is attached across a battery), an electric field develops across the dielectric, causing positive charge to collect on one plate and negative charge to collect on the other plate. If a battery has been attached to a capacitor for a sufficient amount of time, no current can flow through the capacitor. However, if an accelerating or alternating voltage is applied across the leads of the capacitor, a displacement current can flow.


Early capacitors were also known as condensers, a term that is still  occasionally used today. The term was first used for this purpose by Alessandro Volta in 1782, with reference to the device"s ability to store a higher density of electric charge than a normal isolated conductor. 

Capacitors in Series & in Parallel connection 

When capacitors are placed in parallel with one another the total capacitance is simply the sum of all capacitances. This is analogous to the way resistors add when in series.  Much like resistors are a pain to add in parallel, capacitors get funky when placed in series. The total capacitance of all capacitors in series is the inverse of the sum of all inverse capacitances.



Capacitor rating

The effect of a capacitor is known as ‘capacitance.  Like Ohm as a resistance measurement unit of Resistors, Farad is the unit to measure value of a capacitor and is a second parameter of capacitor rating.  This actually indicates how much energy a capacitor can store and termed as its ‘capacitance’.  Value of capacitance varies between picofarad to kilofarad, and following table will explain more of the range: 

Value Name

Short Name


Value in Farads




0.000000000001 F




0.000000001 F




0.000001 F 




0.001 F 




1000 F

There is hardly any electronic circuit which does not contain a capacitor in itThere are many different kinds of capacitors available from very small capacitor beads used in resonance circuits to large power factor correction capacitors, but they all do the same thing, they store charge. Apart from storing electric charge, capacitors also can function to suppress spikes and filter signals. 

 Performance factors 

While deciding about a suitable capacitor for any application, following factors need to be considered:

  • Size - Size both in terms of physical volume and capacitance. It"s not uncommon for a capacitor to be the largest component in a circuit. They can also be very tiny. More capacitance typically requires a larger capacitor.
  • Maximum voltage - Each capacitor is rated for a maximum voltage that can be dropped across it. Some capacitors might be rated for 1.5V, others might be rated for 100V. Exceeding the maximum voltage will usually result in destroying the capacitor.
  • Leakage current - Capacitors aren"t perfect. Every cap is prone to leaking some tiny amount of current through the dielectric, from one terminal to the other. This tiny current loss (usually nanoamps or less) is called leakage. Leakage causes energy stored in the capacitor to slowly, but surely drain away.
  • Equivalent series resistance (ESR) - The terminals of a capacitor aren"t 100% conductive, they"ll always have a tiny amount of resistance (usually less than 0.01O) to them. This resistance becomes a problem when a lot of current runs through the cap, producing heat and power loss.
  • Tolerance - Capacitors also can"t be made to have an exact, precise capacitance. Each cap will be rated for their nominal capacitance, but, depending on the type, the exact value might vary anywhere from ±1% to ±20% of the desired value.

Capacitor types

Capacitors are available in variety of types and they are classified by various parameters as below:

by Material

Capacitors are made in a many of shapes and sizes, all of which determine how well they can hold a charge. The most common type of capacitors are: 

Ceramic Capacitors             

Electrolytic Capacitors

Tantalum Capacitors

Aluminium Capacitors

Paper Capacitors

Mica Capacitors




 Ceramic Capacitors 

These are the most commonly seen capacitors even for simple

electronic projects. Unlike their electrolytic counterparts, ceramic

capacitors hold a smaller charge but also leak less current. They

also are usually the cheapest of capacitors.


Electrolytic Capacitors


These look like small tin cans that we find on a circuit board and can hold a massive electric charge in their tiny footprint. They’re also the only type of capacitor that is polarized, meaning that they will only work when wired in a particular orientation. On these electrolytic capacitors, there’s a positive pin, called the anode, and a negative pin called the cathode.


Despite being able to hold a large amount of an electric charge, electrolytic caps are also well known for leaking current quicker than ceramic caps. Hence, they’re not the best choice when we need to store energy.


Tantalum Capacitors 

Tantalum capacitors are electrolytic capacitors which use tantalum metal for the anode. They are polarized capacitors with superior frequency and stability characteristics.  Tantalum capacitors are made with capacitance values ranging from 1nF all the way to 72mF and they are much smaller in size than aluminium electrolytic capacitors of the same capacitance.

Ceramic capacitors typically specify insulation resistance, whereas tantalum capacitors are graded by direct current leakage (or DCL).


Aluminium Capacitors

 Aluminium capacitors are polarized electrolytic capacitors.  Aluminium

 electrolytic capacitors are found in many applications such as power

supplies and computer motherboards. These capacitors are used when

a large capacitance is required and leakage current is not an important

factor. These capacitors are available in various sizes and shapes


Paper Capacitors 

Paper capacitors are the fixed capacitors that store a fixed amount of electric charge with a fixed capacitance value.  Paper capacitor is also known as a Fixed capacitor, in which paper is used as a dielectric medium, that stores energy in the form of the electrical field. These capacitors are used at power line frequency with a capacitance value of 1nF to 1uF. It stores a fixed amount of electric charge.



Mica Capacitors 

Mica is a silicate mineral found in granites and other rocks. It is frequently used as an electrical insulator in electrical applications. In mica capacitors, mica is used as dielectric material. This dielectric material opposes the flow of electric current or electric charges.  Mica capacitors are generally used when the design calls for stable, reliable capacitors of relatively small values. They are low-loss capacitors, which allow them to be used at high frequencies, and their value does not change much over time. Mica minerals are very stable electrically, chemically and mechanically.



Supercapacitors are the superheroes of the capacitor family, and can store a high amount of energy! Unfortunately, supercapacitors don’t handle excess voltages very well and care needs to be taken to ensure proper voltage in the circuit.

 A supercapacitor, also called an ultracapacitor, is a high-capacity capacitor with a capacitance value much higher than other capacitors, but with lower voltage limits, that bridges the gap between electrolytic capacitors and rechargeable batteries.


Unlike electrolytic capacitors, supercapacitors being used to store and discharge energy, much like a battery. But in contrast to a battery, supercapacitors release their charge all at once!


by Construction 

Capacitor types are also made based on their construction/structure, and most common types are:








Solder lug

Stud threaded





by function 

Decoupling capacitors (to decouple one part of an electrical network (circuit) from another – for shunting noise)

Bypass capacitors (To short AC signals to the ground so as to remove any AC noise present on a DC signal producing a much cleaner and pure DC signal)

Filter capacitors (To filter out certain unwanted frequency or series of frequencies from an electronic circuit – Low Pass [to allow AC and block DC) and High Pass filters (allow high frequency and block low frequency signals)]

Storage capacitors (to store extremely high energy in limited space without sacrificing reliability, quality and degree of accuracy of on-board supply)

Power Capacitors (They provide a static source of reactive power in electrical distribution systems in applications like Power Factor correction, motor starters, power supplies)

Phase-splitting capacitors (This capacitor connected in series with the starting winding creates a phase shift of approximately 80 degrees between the starting and running winding. This results in a higher starting torque, with less starting current).

Phase shifting capacitors (In AC circuits voltage and current are changing continuously, and in a purely capacitive AC circuit the peak value of the voltage waveform occurs a quarter of a cycle after the peak value of the current. Therefore, a phase shift is occurring in the capacitor, the amount of phase shift between voltage and current is +90° for a purely capacitive circuit, with current LEADING the voltage). In Electronics circuits (like phase shift oscillators), capacitors are used to achieve phase shift to get desired results.




















Credits: Wikipedia, Electronics Tutorials, Sparkfun, Autodesk, Mouser, Iskra, ICAR, EPCOS, Kemet, Vishay & other manufacturers (whose images are used)

This is a brief overview of this topic.  The subject itself is vary vast and it’s not expected to cover every aspect here.  Technical details in this article are compiled from best known sources.  These are of course open for any corrections and additions.

                         Views (2065)


Your Name : *
Country: *
City: *
Email ID :
Mobile No:
Company Name:
* Indicates Compulsory Fields