Variable Capacitors

Written by Michael O'Brien
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Variable capacitors are passive components consisting of two plates, which are conductors of electricity. They're separated by an insulator. An insulator does not conduct electricity well. This insulating layer may be made of ceramic, plastic, or even paper.

Variable Capacitors for Storage

A variable capacitor is like a small bottle of electricity just waiting to be released. Generally speaking, the electricity can be stored, like you would put food in Tupperware, to be used later. The insulating layer of material is called the dielectric. Energy is then stored as an electrostatic field.

It's rare that devices are able to store electricity. In fact, the only other electricity "Tupperware" is a battery. Variable capacitors are handy when you want to turn an appliance on or off. The amount of electricity stored, or capacitance, is directly proportional to the plate size. It is also inversely proportional to the length of the separation of the plates. What this means in a nutshell is that the design, shape, and size of the capacitors is what determines how much electricity they store, and for how long.

Radial and Axial Capacitors

Variable capacitors fall into two categories. They can be either radial or axial in nature. Radial capacitors look like they have little legs. The electricity is stored in the top part which looks like a tiny trash can or bucket. They look a bit like air needles you might use when blowing up a basketball. Axial capacitors look basically the same, but have wires coming out of either end instead of just the bottom.


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