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What Are the Differences Between Non-Polarized and Regular Capacitors?

Capacitors are one of the basic components used in most electrical circuitry. They function as a sort of reservoir, gathering an electrical charge, which they can lose on demand. They can be thought of as special-purpose batteries, with only a small capacity but the ability to discharge it very quickly. They come in a number of shapes and sizes and can be either polarized or non-polarized.

An Analogy
- To visualize how a capacitor works, imagine a small bucket sitting beneath a trickle of water. The trickle of water can't do much, but once the bucket is full, it provides a useful amount of water that can boil vegetables or douse a fire. A capacitor works in much the same way. Think of a camera flash. When you turn it on, the flash's battery trickles electricity into the capacitor, like water running into the bucket. Once it is full, the capacitor can provide the relatively large amount of electrical current required by the flash.
Types of Capacitors
- There are several types of capacitors, made from different materials and in various shapes and sizes. Some are flat ceramic disks, some are chubby cylinders and others are irregular rectangles covered in shiny plastic. Electrolytic capacitors, made by growing a thin layer of oxide on the metal they are made from, are common and versatile. Tantalum, Mylar and silver mica are also used.
Polarized vs. Non-Polarized Capacitors
- Low-cost capacitors are usually polarized, meaning that they have specifically designated positive and negative terminals. They must be connected to the circuit the right way or they will self-destruct with an audible "pop" and, occasionally, damage the circuit or an unwary hobbyist's fingers. Non-polarized capacitors are designed to accept an input voltage on either terminal and can be attached either way. They are more complex and more costly to manufacture. To minimize the risk of mistaking one for the other, polarized capacitors are clearly marked with stripes, arrows or other markings to designate the negative terminal.
Common Uses
- Polarized capacitors are commonly used in less demanding applications in order to keep costs down. You will find them used for applications such as noise-filtering on power lines, in inexpensive power supplies and a variety of demonstration-type hobby electronics circuits. Polarized capacitors are available to much higher specifications, making them suitable for more demanding applications, including computers, home electronics and noise filtering for high-end audio equipment.

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