What’s a Capacitor?

Capacitors are used in almost every single electronic device on the planet. Everyday Einstein explores what they do and how they work.

Lee Falin, PhD
3-minute read
Episode #37

When Benjamin Franklin learned about the Leyden jar, he conducted several experiments with it. In one of the experiments, he connected a group of jars together to see if he could store a more powerful charge. The arrangement reminded Franklin of a group of artillery weapons, so he referred to it by the same term, calling it an electrical battery.

Back to the Future

You’re probably thinking, “Sure, thanks for this history lesson, but what has this got to do with capacitors?” I’m glad you asked. Modern capacitors function just like Leyden jars. They store up electricity and then discharge it rapidly.

However, instead of using a glass jar as the insulator, modern capacitors use a variety of materials including plastic, ceramics, and special anodized metals. In modern capacitors this insulating layer is called the dielectric. Just how much charge a capacitor can store depends on the materials it’s made from, as well as its shape and size. The amount of charge a capacitor can hold is called its capacitance and is measured in a unit called farads.

While this description makes capacitors sounds like a one-trick pony, how they are used in relation to other electronic parts give them a wide variety of applications, such as smoothing out power fluctuations, providing rapid bursts of power, and even providing a method of keeping track of time.


Please note that archive episodes of this podcast may include references to Everyday Einstein. Rights of Albert Einstein are used with permission of The Hebrew University of Jerusalem. Represented exclusively by Greenlight.

About the Author

Lee Falin, PhD

Dr. Lee Falin earned a B.S. in Computer Science from the University of Illinois, then went on to obtain a Ph.D. in Genetics, Bioinformatics, and Computational Biology from Virginia Tech.