What is Capacitor or Capacitance Definition and Formula

What is Capacitor or Capacitance? Definition and Formula

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What is capacitor or capacitance? Capacitor definition: There are three fundamental electrical circuit elements, resistor, inductor and capacitor. The capacitor behaves as a charge storage device in an electrical circuit. It holds the electric charge when we apply a voltage across it, and it gives up the stored charge to the circuit as when required. Or capacitor definition: is a passive electronic component that stores energy in the form of an electrostatic field. In its simplest form, a capacitor consists of two conducting plates separated by an insulating material called the dielectric.

The most basic construction of a capacitor consists of two parallel conductors (usually metallic plates) separated by a dielectric material. When we connect a voltage source across the capacitor, the conductor (capacitor plate) attached to the positive terminal of the source becomes positively charged, and the conductor (capacitor plate) connected to the negative terminal of the source becomes negatively charged.

What is Capacitor or Capacitance? Definition and Formula

Because of the presence of dielectric in between the conductors, ideally, no charge can migrate from one plate to other. So, there will be a difference in charging level between these two conductors (plates).

Therefore an electric potential difference appears across the plates. The charge accumulation in the capacitor plates is not instantaneous rather it is gradually changing. The voltage appears across the capacitor exponentially rises untill it becomes equal to that of the connected voltage source.


Now we understand that the charge accumulation in the conductors (plates) causes the voltage or potential difference across the capacitor. The quantity of charge accumulated in the capacitor for developing a particular voltage across the capacitor is referred to as the charge holding capacity of the capacitor.

We measure this charge accumulation capability of a capacitor in a unit called capacitance. The capacitance is the charge gets stored in a capacitor for developing 1 volt potential difference across it.

Capacitor (Capacitance) Formula

Hence, there is a direct relationship between the charge and voltage of a capacitor. The charge accumulated in the capacitor is directly proportional to the voltage developed across the capacitor.


Q is the charge and

V is the voltage.

Here C is the constant of proportionality, and this is capacitance.

The capacitance depends upon three physical factors, and these are the active area of the capacitor conductor (plates), the distance between the conductors (plates) and permittivity of the dielectric medium.

Here, ε is permittivity of the dielectric medium, A is the active area of the plate and d is the perpendicular distance between the plates.

The standard unit of capacitance is the farad, abbreviated. This is a large unit; more common units are the microfarad, abbreviated µF (1 µF =10-6F) and the picofarad, abbreviated pF (1 pF = 10-12 F).

Capacitors can be fabricated onto integrated circuit (IC) chips. They are commonly used in conjunction with transistors in dynamic random access memory (DRAM).

The capacitors help maintain the contents of memory. Because of their tiny physical size, these components have low capacitance. They must be recharged thousands of times per second or the DRAM will lose its data.

Large capacitors are used in the power supplies of electronic equipment o fall types, including computers and their peripherals. In these systems,the capacitors smooth out the rectified utility AC, providing pure, battery-like DC.

Capacitor (Capacitance) Conclusion

After going through the above portion of capacitor (capacitance) explanation we can now establish a capacitor definition. I hope you enjoy when reading this article, thank you.