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What Is A Capacitor?

Electricians and Energy Topics
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In a way, a capacitor is like a battery, in that both are designed to store electrical energy. But whereas batteries produce electrons on one terminal and absorb them on the other, capacitors work more simply, not producing electrons but only storing them. Energy is held for a short time in an electric field between the capacitor’s 2 charged plates before being released. The result is that a capacitor can dump its entire charge in a fraction of a second, while a battery would need more time to fully discharge. Here is some basic information regarding how a capacitor works and the ways in which it contributes to our technology.

How a Capacitor Works

A capacitor contains 2 conductive metal plates, each of which hosts an opposite charge. These plates are separated by a non-conducting material called a dielectric or other type of insulator. As a current is applied, separate charges in turn build up on the 2 plates. The energy that results from those charges is then stored in the insulator/dielectric field that lies between them. Many materials can be used as a dielectric and usually are selected based on what the capacitor is intended for. For instance, if high temperatures and voltages are a factor, then mica or glass might be a good choice. On the other hand, Mylar is good for timer circuits and ceramic is ideal for high-frequency purposes like antennas and x-rays.

Capacitors work in a circuit alongside a battery. When you connect the two, the plate on the capacitor that attaches to the battery’s negative terminal accepts the electrons the battery is producing, while the plate attached to the positive terminal loses electrons to that battery. Once charged, the capacitor holds the same voltage as the battery (a capacitor’s storage potential is known as capacitance). In this type of circuit, the capacitor works as a storage center, essentially storing the excess electrons produced by the battery. Then when there’s an increase in demand or a need for this energy, the capacitor will release them.

What a Capacitor Is Used For

What’s great about capacitors is how quickly they are able to drop their charge. Thus, they end up being used in several different ways in electrical circuits. Capacitors are often used to store charge for high-speed use. The most recognizable example of this is the electronic flash on a camera, since the capacitor can dump the full charge into the flash immediately for an instant response. Capacitors can also be used to “clean up” electric signals, removing any ripples or spikes in the voltage. This cleaner energy flow results in higher efficiency and a better operating product. A variable capacitor, for example, is able to adjust the frequency and timing of telecommunications equipment. Capacitors can also be used to block DV voltage.

Just like a battery, a capacitor provides energy storage that has the potential to lead to new innovations and options in the technological world. Capacitors can be a great addition to an electrical circuit, providing cleaner and more instantaneous power when needed.

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