How to Tell Positive and Negative on a Capacitor

Capacitors on a circuit board
There are different types of capacitors, but only one type is polarized: the electrolytic capacitor. Compared to non-polarized capacitors, electrolytic capacitors are more expensive and have to be installed in a specific direction to function properly, but they have higher capacitance — or the ability to hold more charge. Read on to find out how to tell positive and negative on a capacitor and to learn more about non-polarized devices.

What Is A Capacitor?

A capacitor is an electronic component that stores electrical energy in an electric field. It is a passive electronic component with two terminals. A capacitor consists of two conductors separated by a non-conductive region. The non-conductive region can either be a vacuum or an electrical insulator material known as a dielectric (such as glass, air, paper, plastic, & ceramic).

Here are some of the ways capacitors are used in electronic devices:

  • Amplifiers: Capacitors are used in amplifiers to store energy and then release it to the output signal. This helps to smooth out the output signal and make it more accurate.
  • Oscillators: Capacitors are used in oscillators to create a periodic output signal. This is used in a wide variety of electronic devices, such as radios and clocks.
  • Filters: Capacitors are used in filters to remove unwanted frequencies from an input signal. This is used in a wide variety of electronic devices, such as audio amplifiers and power supplies.
  • Rectifiers: Capacitors are used in rectifiers to store energy from an alternating current (AC) source and then release it as a direct current (DC) signal. This is used in a wide variety of electronic devices, such as power supplies and solar cells.
  • Power supplies: Capacitors are used in power supplies to store energy and then release it to the output circuit. This helps to smooth out the output voltage and make it more stable.

Capacitor Polarization

When you connect voltage to an electrolytic capacitor’s terminals, the polarity must be correct or the capacitor’s oxide layer can be damaged. This creates a large current flow and the eventual destruction of the capacitor. So, how do you tell which sides are positive and negative? Most electrolytic capacitors are clearly marked with a black stripe on the negative side and include arrows or chevrons to deter incorrect connections. Unmarked polarized capacitors have an indented ring around the positive end.

Types of Non-Polarized Capacitors

Non-polarized capacitors come in different shapes and sizes. They don’t have the capacitance of polarized capacitors, but they’re cheaper and more readily available. Here are a few of the most commonly seen:

  • Ceramic capacitors
  • Silver mica capacitors
  • Polyester capacitors
  • Polypropylene capacitors
  • Teflon capacitors
  • Glass capacitors

Find the Parts You Need at Gateway Cable Company

Need assistance with choosing the right capacitor for your operation? Gateway Cable Company can help! Contact us for a quote on any of our products and to learn more about polarized and non-polarized capacitors. We’re also a reliable source for more information on other electrical components, such as twisted pair cables and terminal blocks.