What is Capacitor and How Does it Work?

Capacitors are integral parts of any electrical and electronic device. Also known as condensers, capacitors play a crucial role in storing energy. Whether you take a photo with a digital camera, swipe the channels on your HDTV or tune into your favourite radio station - capacitors are being used in all of these instances.

As one of the most used and common electrical goods, capacitors come in a wide variety for use in different appliances and devices. While capacitors have been used for quite some time now and have immense benefits, they also come with some disadvantages. 

If you want to know about capacitors, in this article, we will discuss everything about capacitors, from what are capacitors and how they work to the different types of capacitors and their various advantages and disadvantages of them. 

What is a capacitor?

To describe it simply, a capacitor is a device that is used for storing electrical energy inside an electric field and using that stored energy later on for different purposes in the devices and appliances it is connected to. A capacitor has similarities with a battery, but its function is different from that of a battery. In batteries, chemicals are used for storing electrical energy and the release of this stored energy through the battery circuit is quite slow. However, in the case of a capacitor, the stored energy release takes place rapidly. Capacitors can take a while to charge. But once they are fully charged, they can start working instantly. 

A capacitor has two electrical conductors and they are separated by an insulator. The two conductors inside the capacitor are wired to two terminals, i.e. electrical connections. A capacitor can be charged by wiring it simply into an electric circuit. Charging is when you add electrical energy to a capacitor and discharging is when you release the energy from the capacitor. 

Capacitors come in different varieties. We will discuss the common capacitor types in this next section.

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Common Types of Capacitors

Variable capacitors and fixed capacitors are the two main types of capacitors. While fixed capacitors have fixed capacitance values, variable capacitors have adjustable capacitance values. These two groups again contain different types of capacitors for use in different electronic/electrical devices. Some of the most commonly used capacitors include the following:

• Super capacitor

Also known as ultra-capacitor or more commonly, the supercap, super capacitors are the most popularly used capacitors. The speciality of these capacitors is that they provide large values of capacitance going up to almost several thousand Farads. The use of these capacitors is commonly seen in systems requiring memory hold-up supply and in various automotive applications. 

• Electrolytic capacitor

If you are looking for a capacitor for low-frequency applications like power supplies applications or audio coupling applications, using electrolytic capacitors is the best option. This is a polarized capacitor, which has the capacity of providing high capacitance values, that is somewhere near above 1µF. 

• Silver Mica capacitor

When you are looking for higher levels of stability, you cannot go wrong with a silver mica capacitor. Along with providing high accuracy, these capacitors offer a low energy loss. The use of these capacitors is mainly seen in RF applications, providing maximum values of 1000 µF. Though they are quite useful, they are not high on the popularity index as other capacitors. 

• Film and Paper capacitors

When it comes to film capacitors, you will find varieties like metalized polyester film capacitors or polystyrene film capacitors. These capacitors are designed in a specific manner to suit various needs. 

Metalized polyester film capacitors are smaller when compared to regular polyester film capacitors. The former capacitors have very thin electrodes and therefore they can fit into a smaller package. 

Film capacitors, on the other hand, are economical capacitors containing limited frequency response to a few hundred kHz. They offer close-tolerance capacitors (5% or 10%) for important applications. Most importantly, these capacitors are extremely affordable too. 

• Ceramic capacitors

While discussing the types of capacitors, you cannot miss ceramic capacitors. These capacitors are used in various applications like RF and audio. They are highly reliable and economical at the same time. The values of ceramic capacitors start from pico-Farads to 0.1 micro-Farads. The dielectric in the system determines the energy loss factor, but usually, the value is extremely low. 

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How Does a Capacitor Work – Functioning of a Capacitor

A capacitor also comes with two electrodes, just like a battery. However, in the capacitor, the electrodes are connected to two metal plates, which are separated by a dielectric. The function of the dielectric is that it doesn’t conduct electricity as it does not allow the metal plates to come in contact with one another. 

When power is supplied to the two electrodes, electrons start gathering on one of the electrodes, making it negatively charged. The other electrode has a deficiency of electrons and is positively charged. Even after removing the power supply, this state continues. The electric charge gets accumulated between the two electrodes. When the dielectric is inserted between the electrodes, the polarization increases the accumulated charge. This amount of charge stored in the capacitor is called its capacitance range. 

Charging a capacitor is the above-mentioned process of storing charge in the capacitor. On the other hand, the discharge process is about releasing this stored charge from the capacitor to the connected intended device or appliance. 

Advantages and Disadvantages of Capacitors

It is said that all items come with their share of advantages and disadvantages. Capacitors are nothing different and they have their own sets of pros and cons as well. Let us take a look at the various advantages and disadvantages of capacitors:

Advantages of capacitors

The majority of electrical systems and circuits have capacitors in them. Some of the prominent benefits and advantages of having capacitors within appliances and devices include:

• Capacitors can store energy quickly
• Along with storing energy, capacitors can release energy rapidly as well
• Energy losses are very low and can be considered negligible 
• The way of operation is pretty simple yet extremely effective
• Minimal to almost no maintenance is required
• Components that are used for making capacitors are relatively cheap
• Capacitors can operate in both DC and AC electrical circuits
• Available in a wide variety of sizes, types, and operating voltage ranges
• They come with long service life
• Capacitors are readily available in the market

Also Read: The Downsides Of Voltage Fluctuations

Disadvantages of capacitors

Capacitors come with certain disadvantages and drawbacks as well. Some of the cons are as mentioned below:

• There is eventual depletion of the stored energy if left unused
• Capacitors come with limited energy storage
• When compared to batteries, capacitors have a lesser capacity for energy storage
• There can be variations in the stored voltage levels within a capacitor

Find the best quality capacitors at the Schneider Electric store

Capacitors are widely available in the market. However, before you purchase them, you have to make sure that they are suitable for your requirements and are of good quality. One of the best places where you will find a wide variety of capacitors at the best rates is the Schneider Electric store.