The Operation of a Capacitor

A capacitor is a battery-like device that works via a different technique. While capacitors and batteries both stock electrical energy, they operate differently. A battery comprises two terminals; on one side, electrons are produced due to chemical reactions, while the other collects them when we make a circuit. However, a capacitor is way more straightforward as it cannot create new electrons and only stores them. A capacitor contains the highest amount of charge in relation to its capacitance with respect to its voltage.

Types of Capacitors

Capacitors can serve different purposes; the tiniest capacitors made can be used in calculators, while an ultra-capacitor can provide power to a bus. Let’s take a look at various types of capacitors and how they are used:

Air capacitors: Air capacitors use air as their dielectric and are frequently used in the tuning circuits of FM radios.

Mylar capacitors: Mylar capacitors can tolerate high voltages in small packages and are generally used for circuits related to time-frequency such as clocks, alarm clocks, etc.

Glass capacitors: Glass capacitors are suitable for use in places with high-voltage applications.

Ceramic capacitors: Ceramic capacitors use ceramic as the dielectric and are generally used for high-frequency elements such as antennas, X-ray machines, MRI machines, etc.

Supercapacitors: Supercapacitors provide power to various electric and hybrid motor vehicles.

Materials Used to Create Capacitors

In a basic capacitor, the terminals get linked to two metal plates separated by a non-conducting element or a dielectric. For example, a capacitor can be easily created with two pieces of aluminium sheet and a single piece of paper, including some electrical clips, to give it a finishing touch. Although it will not be exactly like a professional capacitor, it will be able to function with minimal storage capacity. According to theoretical concepts, any non-conductive substance can be dielectric. However, certain specific materials are practically used for capacitors to function in the best possible way. Mica, cellulose, ceramic, porcelain, Teflon, mylar and air are certain non-conductive materials generally used for better results. Moreover, the dielectric determines the type of capacitor, how it will function and its purpose. Depending on their type and size, some capacitors are used for higher frequencies while others are suitable for higher voltage applications.

Capacitor Circuit

When we link a capacitor to a battery, the following happens:

• The plate on the capacitor linked to the battery’s negative terminal gains electrons produced by the battery.
• The plate on the capacitor linked to the battery’s positive terminal drops electrons into the battery.
• Once the capacitor is charged, it has equal voltage as the battery, such as two volts on the battery and two volts on the capacitor. The power of storing charges depends on the size of the capacitor. 

Working of a Capacitor

A metal typically comprises an equivalent amount of positively charged and negatively charged particles; therefore, it is electrically neutral. When we connect a battery or a source of power to the plates of metal on a capacitor, a current starts flowing. Moreover, electrons from the plate attached to the positive lead of the power source, i.e., the battery, will move towards the plate linked to the negative lead of the power source. However, the electrons will not be able to pass through the capacitor due to the dielectric among the plates. Therefore, the electrons will start to collect on the plate. After a particular amount of collection, the battery will be left with a little energy that will be inadequate to push any new electrons inside the plate. At this point, the capacitor is charged. Moreover, the initial plate has developed a net negative charge and the second plate has formed an equivalent net positive charge. An electric field appears across the capacitor that is attractive in nature and carries the capacitor’s charge.

Charging Time of a Capacitor

It takes five-time constants for a capacitor to get charged to the supply voltage. Moreover, a specific formula is used to calculate the charging time of the capacitor:

Formula: τ = RC

Conclusion

A capacitor is a device with two terminals and possesses the capacity to store energy in the form of an electric field. Moreover, it has two electrical conductors separated by a distance. A capacitor has two basic functions–charging as well as discharging at the same time. It works in AC as well as DC circuits