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How Capacitors Works- All You need to Know

Almost all electric circuits have at least one capacitor on them. Together with inductors and resistors, capacitors make up the three basic components highly useful in electronics. 

Knowing the principle of capacitors’ construction and their working can help you navigate the science of electronics in general. 

Read along to discover more about capacitors.   


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What are Capacitors?


Capacitors and Microchips

Figure 1: Capacitors and Microchips


A capacitor is an electrical component useful in energy storage in the form of an electrical charge. 

The types of practical capacitors may vary broadly. However, all capacitors contain a minimum of two capacitor plates (electrical conductors). An insulator (dielectric) separates the electrical plates of a capacitor. 

The SI unit of capacitance measures the charge in a capacitor.


Capacitor Construction


Capacitors in a Circuit Board

Figure 2: Capacitors in a Circuit Board


Usually, the capacitor plates must be conductive plates and made of materials such as tantalum and aluminum. On the other hand, a capacitor's dielectric material can be insulating glass, plastic, ceramic, or paper. 

The primary function of dielectric material is to provide insulation between the capacitor plates.  Hence, it obstructs the flow of the direct current. 

The functionality of a capacitor, the capacitance, is measured in farads. Effective capacitance is directly proportional to the surface area of the electric plates. It is also proportional to the permittivity, ε of the insulating material used. 

Consequently, the closer the positions of the electric plates, the higher the capacitances.

With this information in mind, let us dig deeper to discover the various types of capacitors and their use methodologies. 


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Different Types of Capacitors and Their use Methods


Electronics Repair

Figure 3: Electronics Repair




These are capacitors that utilize air as their dielectric material in between the capacitor plates. Usually, air capacitors contain a relatively small capacitance value ranging from 100pF and 1nF. 

Due to the nature of air as dielectric material, an air capacitor is a larger capacitor to increase the capacitance levels. Thus, it is unfavorable to use in most electrical circuits. Air capacitors are common in radio tuning circuits. 




It is a special capacitor with unique features compared to electrolytic and other capacitors such as plastic film capacitors. Mylar capacitors can withstand high voltage difference values in a small package. 

More so, the capacitors offer high resistance against external factors such as moisture.  Often, manufacturers use Mylar capacitors in timer circuits such as counters, alarms, and clocks.  


How Capacitors Works--Glass


A glass film capacitor is usually solid, and it generally operates, ranging from 10 pF to 1,000 pF. Most glass capacitors are costly; hence they are used in lucrative devices. Glass capacitors are suitable for high-voltage applications. 


How Capacitors Works--Ceramic


Historically, ceramic was among the first insulating materials to be used in the production of capacitors. 

Due to the factors such as size, electrical characteristics, and parasitic capacitance effects, ceramic capacitors have several geometries. Examples include barrier layer capacitors and ceramic tubular capacitors.

Ceramic capacitors are subdivided into two major types; ceramic disc capacitors (CDC) and multilayer ceramic capacitors (MLCC). 

Manufacturers use surface-mounted technology to produce multilayer ceramic capacitors. The MLCCs are usually smaller in size, making them favorable to use in most electronic circuits. 

MLCCs are mostly between 1nF and 1µF. in some instances, and this value can go up to 100µF.

Also, manufacturers coat a ceramic disc with silver films on both sides to produce a CDC. This coating technique helps in reducing the loss of capacitance of the CDC. 

As a result of parasitic effects such as inductance and resistance, ceramic capacitors provide high-frequency responses. You can find Most ceramic capacitors in high-frequency circuits such as X-rays, MRI machines, and antennas.  

A ceramic capacitor is a common type of capacitor used in various circuits worldwide. 

How Capacitors Works--Supercapacitors


A Circuit Board

Figure 4: A Circuit Board


They are capacitors with electrochemical capacities boosting high capacitance levels compared to other capacitors. Manufacturers can categorize supercapacitors among the electrolytic capacitors. Alternatively, they describe them as rechargeable batteries known as an ultracapacitor. 


How Does a Capacitor Work?



Figure 5: Capacitors


All metals have equal amounts of positively charged and negatively charged particles. Therefore, metal is electrically neutral. 

An electric current (DC or AC) flows when connecting any power flow to the electric plates. The electrons move from the battery through the positive metal plate to the negative metal wire. The positive plate acts as a positive terminal, while the negative terminal acts as a negative terminal. 

A dielectric between the plates prevents the electrons from passing through the capacitor, accumulating on the electrical receptacles. 

When electrons saturate the electronic conductors, the battery loses electrical energy to push more electronics into the capacitor. The already moved electrons repel any new ones. Therefore, the capacitor acquires full charge. 

The positive plate acquires a net negative charge, and the negative plate attains an equal positive order. Hence, the capacitor has an electric field that holds the tabs on the conductive plates. 


Capacitors Application Examples


Capacitors in an Electronic Component

Figure 6: Capacitors in an Electronic Component


Decoupling (Bypass) Capacitors


A decoupling capacitor is primarily coupled with integrated circuits between the IC and the power source. 

They filter noise in the output of power supplies, such as voltage ripples. Whenever something interrupts the power supply, Bypass capacitors supply power, hence bypassing the power supply. 

A capacitor acts as a power supply when the main power source switches off. It’s also useful in instances when there is power loss. 


How Capacitors Works-- Signal Filtering 


Capacitors use their specific response periods to block low-frequency signals but allow high frequencies through. 

In radio receivers, capacitors help in tuning out undesired frequencies—moreover, capacitors filter frequencies in woofers. 


How Capacitors Works--Capacitors as Electrical Energy Storage


Storage of electric energy is another important use of capacitors. A capacitor stores a relatively more minor amount of energy than a small battery. However, they last considerably longer and deliver electric power faster. Therefore, capacitors are suitable to use in circuits requiring a high burst of energy.




Understanding the composition of a capacitor is central to knowing its mode of operation. We have laid down all the critical perspectives of these devices. 

We hope that we've solved all the questions that you had about these devices. If not, worry not. You can reach out to us anytime, and we will provide answers to all your questions. 



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