Before revision: Center positive symbol Center negative symbol Polarity symbols are a notation found on electrical devices that use direct current (DC) power, when this is or may be provided from an alternating current (AC) source via an AC adapter.
After revision: Center positive symbol Center negative symbol Polarity symbols are a notation for electrical polarity, found on devices that use direct current (DC) power, when this is or may be provided from an alternating current (AC) source via an AC adapter.