What is a Capacitor? And its types

What is a capacitor?

A capacitor or also known as a capacitor is a device capable of storing energy through electric fields (one positive and one negative). This is classified within the passive components since it does not have the ability to amplify or cut the electrical flow.

Capacitors are mainly used as direct current filters, as they prevent sudden changes and noise in the signals due to their operation.

Parts of a capacitor

This device in terms of construction is too simple compared to other components since it only consists of three essential parts.

  • Metal plates: These plates are responsible for storing electrical charges.
  • Dialectical or insulating: It serves to avoid contact between the two plates.
  • Plastic Housing: Covers the internal parts of the capacitor.

How does a capacitor work?

In their natural state, each of the inner plates has the same number of electrons. When we connect a voltage source one of the plates loses electrons (this being the positive terminal), while the other one gains them (negative terminal). This movement of electrons stops when the capacitor reaches the same voltage as the power supply.

The dialectical material is placed between the two plates and serves to prevent them from making contact with each other, it also serves to prevent the electrons from passing from one to the other.

When the power supply is disconnected, the electrons gained by one of the plates return to the other plate to reach its natural state with the same number of electrons in each.

Capacitor types

There are different types of capacitors, either due to their type of material, their construction, their operation, etc. This time we will classify them in a more general way.



Although there are non-polarized electrolytic capacitors, they are not as common as polarized capacitors, this is because they are used in direct current where there is always a negative and a positive pole. These types of capacitors have a predefined useful life and even if they are not used they deteriorate over time.

Its applications are related to power supplies or filters. To identify the terminal of these devices, all you have to do is look for the color stripe inside the case or also identify the shortest terminal.

Electrolytic capacitor


Some of its main characteristics are: that it has no polarity, that it has a code printed on one of its faces, of which the first two numbers indicate the value and the third number is the number of zeros added to it, »the value it is always encoded in peak farads ».

They are used for filters, oscillators, or to couple different circuits. One of their disadvantages is that they are quite sensitive to changes in temperature and voltage.

Ceramic capacitor

From  movie

The material used for this capacitor is plastic, they are non-polarized and have a self-healing capacity, they are mainly used in audio applications.

Film capacitor

Of mica

They are used when great stability is required, either by temperature or by time, also when there is a high electrical charge.

Mainly used in high voltage industrial applications, valve amplifiers and where precision is one of the important factors

Mica Capacitor

Double-layer electrical or supercapacitors

These capacitors are like the electrolytic ones but they store thousands of times more energy, the conventional ones by the regular ones are in the order of the micro-farads and these super-capacitors can reach the order of 3,000 farads.

Double layer capacitor


These capacitors have the advantage of being able to vary their value within the ranges established by the manufacture. This is achieved thanks to the sliding of the conductive plates.

They are used in filters and in tuning applications.

Variable capacitor