How Capacitors Make Your Electronics Usable

19 May, 2019 | Quest Components

How Capacitors Make Your Electronics Usable

Like a battery, a capacitor stores electrical energy. Unlike a battery, though, a capacitor cannot produce new electrons. Without capacitors, electronic devices could not function. Here’s how they work.

What Is a Capacitor?

The terminals inside a capacitor are connected to two metal plates separated by a dielectric, which is simply a non-conductive substance. A simple example would be two sheets of aluminum foil separated by a piece of paper.

Capacitors vary in size and type, and in which materials are used. Capacitors range from tiny plastic pieces inside a calculator to glass capacitors used in deploying space probes to ultra-capacitors that power commuter buses. Some common types of capacitors include:

  • Ceramic: High frequency applications
  • Tantalum: High reliability applications
  • Electrolytic: Higher capacitance capabilities than other types
  • Mylar: Timers such as clocks and alarms
  • Glass: High voltage applications
  • Air: Radio tuning circuits
  • Super Capacitor: Electric and hybrid cars

How a Capacitor Works

A capacitor functions like a water tower for electrical energy. When the system produces more than is needed, the excess is stored in the capacitor (or water tower). When more is needed than produced, it is released back into the system.

When a capacitor is connected to a battery, two things happen. The metal plate attached to the negative battery terminal accepts electrons, while the plate connected to the positive terminal releases them. When charged, the capacitor’s voltage matches that of the battery.

If a light bulb is added to the circuit, it will light up as current flows from the battery to the capacitor. As the capacitor reaches its capacity, though, the bulb dims and goes out. If you replace the battery with a metal wire, current will flow through the wire from one metal plate to the other. Again, the bulb will light up as the current flows, and then dim and go out as the capacitor drains. You can replace the light bulb with any electronic device, and the circuit will work in the same way.

Storage Potential

The storage potential of a capacitor is measured in farads. One farad is 1 coulomb of charge at 1 volt, and 1 coulomb represents 6.25e18 (6.25 billion billion) electrons. One amp is 1 coulomb of electrons per second. This means that a 1 farad capacitor has the potential to store 1 amp-second of electrons at 1 volt. In practicality, though, a 1 farad capacitor would be ridiculously large for most applications, so capacitors are generally measured in microfarads (1 microfarad is one one-millionth of a farad). Capacitors can dump their full charge in a fraction of a second, making them ideal for high speed applications.

Ready to Get Started?

Here at Quest Components, we are committed to providing you with the information you need to help your business continue to run smoothly. An ISO 9001:2015 Certified Company headquartered in Industry, CA, Quest Components specializes in passive and active board level components. We also provide a variety of services to OEMs (original equipment manufacturers) and CEMs (contract electronics manufacturers) across the globe. Contact Quest Components today at 626-333-5858 for all your electronic component needs!

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