One can find capacitors in almost every sort of electronic circuit from Analog to Logical ones and the selection of a suitable capacitor has great significance as it can affect the functionality of a circuit remarkably. It means that the whole circuit may not function effectively if a suitable capacitor is not placed. Let’s discuss the theory initially in this post “Capacitor Theory”.

What is a Capacitor

The capacitor is a basic electronic component which accumulates electrical charge. When an electric power is provided to the capacitor, the capacitor starts accumulating the electrical charge. As soon as the power goes off, it slowly discharges the accumulated charge. The Various symbols of Capacitors are :
Capacitor theory symbl

Read About How a Capacitor Works in Detail

Inner Construction of Capacitor

A capacitor contains two conductor plates well insulated by a thin layer of Dielectric. The conductor plates may be metal foil or solid metal plates. The dielectric may be any insulating material ranging from vacuum, air, paper, plastics, ceramic etc. The main factor behind categorization of capacitors into its various types is the selection of this dielectric material.

Capacitor theory const
Inner construction of a capacitor

Capacitance

Capacitance has a very important role in Capacitor Theory. The capacitance of a capacitor is its charge storing capability per unit volt. It is measured in Farad. Capacitance of Capacitor can be derived as:

Capacitance, C = Total charge stored/Volt

» C = q/v

What is a Farad I How to Define a Farad

As we know that C=q/v,

Hence, A Farad can be defined as :

A capacitor is said to have a capacitance of one ‘Farad’ when one coulomb of electric charge can be stored in it by applying one volt from a power source.

Here, don’t underestimate one Farad of electric charge. One Farad of charge is beyond limit for most of the electronic circuits. It is therefore, capacitors are commonly available in much smaller capacitance value known as Micro Farad (µ)[ 10-6], Nano farad (n) [ 10-9]and Pico Farad (p) [ 10-12].

Other Basic Terminologies Relevant to Capacitors

Here is a list of some basic terminologies that you must know while reading about Capacitors:

1. What is Dielectric

The dielectric is the insulating material placed between the plates of a capacitor. It determines the capacitance by affecting how much charge the plates can hold at a given voltage. Dielectrics can be made from materials like ceramic, paper, plastic, or electrolytes, each having distinct properties affecting the capacitor’s performance.

2. Electrodes/Plates

Capacitors have two conducting surfaces or plates that store the electrical charge. These plates can be made from materials like aluminum, tantalum, or other metals, providing a surface for the accumulation and storage of charge.

3. Voltage Rating

Capacitors have a maximum voltage they can withstand across their terminals without breaking down the dielectric. The voltage rating indicates the maximum safe voltage that can be applied to the capacitor without causing damage or breakdown of the dielectric.

4. Charge and Discharge

Capacitors store and release electrical charge. When connected to a voltage source, they accumulate charge on their plates. Upon disconnection, capacitors can discharge stored energy, providing a transient current flow in a circuit.

Read more about Capacitor's Charging and Discharging Cycle

5. Parallel and Series Capacitors

Capacitors can be connected in parallel or in series within a circuit. In parallel, the total capacitance increases, while in series, the reciprocal of the total capacitance decreases, impacting the overall capacitance in a circuit.

Read about Various Types of Capacitors
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Capacitor charging and discharging cycle
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