Polarity symbols are a notation for

electrical polarity The following Outline (list), outline is provided as an overview of and topical guide to electrical polarity (also called electric polarity). Positive and negative polarity * In electrical engineering, electrical polarity defines the direction ...

, found on devices that use

direct current Direct current (DC) is one-directional electric current, flow of electric charge. An electrochemical cell is a prime example of DC power. Direct current may flow through a conductor (material), conductor such as a wire, but can also flow throug ...

(DC) power, when this is or may be provided from an

alternating current Alternating current (AC) is an electric current that periodically reverses direction and changes its magnitude continuously with time, in contrast to direct current (DC), which flows only in one direction. Alternating current is the form in w ...

(AC) source via an

AC adapter An AC adapter or AC/DC adapter (also called a wall charger, power adapter, power brick, or wall wart) is a type of external power supply, often enclosed in a case similar to an AC plug. AC adapters deliver electric power to devices that la ...

. The adapter typically supplies power to the device through a thin electrical cord which terminates in a

coaxial power connector A coaxial power connector is an electrical DC connector, power connector used for attaching extra-low voltage devices such as consumer electronics to external electricity. Also known as barrel connectors, concentric barrel connectors or tip con ...

often referred to as a "barrel plug" (so-named because of its cylindrical shape). The polarity of the adapter cord and plug must match the polarity of the device, meaning that the positive contact of the plug must mate with the positive contact in the receptacle, and the negative plug contact must mate with the negative receptacle contact. Since there is no standardization of these plugs, a polarity symbol is typically printed on the case indicating which type of plug is needed. The commonly used symbol denoting the polarity of a device or adapter consists of a black dot with a line leading to the right and a broken circle (like the letter "C") surrounding the dot and with a line leading to the left. At the ends of the lines leading right and left are found a plus sign (+), meaning positive, also sometimes referred to as "hot", and a minus sign (−), meaning negative, also sometimes referred to as "neutral". The symbol connected to the dot (usually the symbol found to the right) denotes the polarity of the center/tip, whereas the symbol connected to the broken circle denotes the polarity of the barrel/ring. When a device or adapter is described simply as having "positive polarity" or "negative polarity", this denotes the polarity of the center/tip.

External links

* {{Cite web , archive-url=https://web.archive.org/web/20150317130637/https://www.accesscomms.com.au/reference/polarity.htm , url=https://www.accesscomms.com.au/reference/polarity.htm , title=Power Supply Units Abbreviations and Symbols , archive-date=2015-03-17
Electric Current Symbols

Electrical engineering