Capacitors and Applications of Capacitors in Circuits

Capacitors are electronic components commonly found in circuits. So what is the specific construction of a capacitor? What is the principle of operation of the capacitor, and how is it applied to the circuit? Follow along with the article below to get answers to questions related to this type of component!

Learn about capacitors

What is a capacitor?

What is a capacitor? Capacitors are a type of passive electronic component that has two conductors separated by an insulating layer. When an electric current passes through, the faces will appear to have opposite charges.

The accumulation of charge at the two terminals gives the capacitor the ability to store electric field energy at the two surfaces, and it can release an electric charge when needed. When there is a difference in AC voltage, the charge accumulation of the capacitor will be behind the phase compared to the voltage. From there, the capacitor creates impedance in the AC circuit.

The principle of operation of the capacitor

The principle of operation of a capacitor is like that of a miniature battery. So what is the difference between a capacitor and a battery? As you know, electric current is the movement of electrons. Capacitors have the ability to efficiently store electrons and when needed, release this charge to generate an electric current. Batteries produce only an electron charge. In its true sense, the capacitor will operate according to the principles of discharge and charge, as illustrated as follows:

• Capacitor charging: Lock S1 is closed, lock S2 is open, and the current from the source will pass through to the capacitor. When fully charged, the capacitor will no longer accept the charge, and the current in the circuit will decrease to zero.
• Capacitor discharge: With S1 locked and S2 closed, the capacitor will be discharged. When it discharges all the charge in the capacitor, the current in the circuit will also go to 0.

The principle of discharge charge of the capacitor exhibits characteristic properties with the ability to conduct AC.

Construction of the capacitor

The specific structure of the capacitor consists of two parallel poles, and in the middle, there is an insulating layer called a dielectric. Dielectrics used for capacitors are non-conductive materials such as glass, mica, paper, ceramics, etc.

Capacitors are classified based on the insulating material used for the capacitor. For example, if the insulating material is paper, the capacitor is called a paper capacitor, if it is ceramic, it is called a ceramic capacitor; and if it uses chemicals, it is called a chemical capacitor.

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Applications of capacitors in circuits

Capacitors are an important component in electronic circuits. Specifically, it is applied for the following purposes:

• Regulate the voltage on the power boards, making the current more stable.
• Generate pulses and create oscillations by transmitting signals between amplifier stages with a difference in DC voltage.
• Most commonly used in power circuits, fan speed reduction circuits, charging circuits of mosquito rackets…
• Create a phase difference between two windings in single-phase AC motors of devices such as fans, and water pumps,…

Unit, symbol, and formula for capacitance

Capacitors are denoted by the letter C. The unit of measurement for a capacitor is called capacitance. Capacitance represents the ability to charge the two terminals of the capacitor. It depends on the area of the plate, the material of the dielectric, and the distance between the two plates. 

The formula for calculating capacitance is as follows: C = x S / d

In there:

• C : capacitor capacitance
• ξ : dielectric constant of the insulating layer between the two plates
• d : thickness of insulation.
• S : surface area of the capacitor plate.

The unit used to measure the value of a capacitor is Fara, abbreviated as F .

In fact, the capacitor used is very small compared to 1Fara. Therefore, there will be commonly used units of conversion such as MicroFara (µF), NanoFara (nF), PicoFara (pF).

• 1 Fara = 1,000,000 µF = 1,000,000,000 nF = 1,000,000,000,000 pF
• 1 Fara = 1000 nF
• 1 n Fara = 1000 pF

Above are answers to questions related to what is a capacitor. Hopefully, through this article, everyone has learned more useful information about capacitors. In the next article, Thetech will introduce everyone to solder flux used in the electrical industry.