Although DC stands for "direct current", DC often refers to "constant polarity". Under this definition, DC voltages can vary in time, as seen in the raw output of a rectifier or the fluctuating voice signal on a telephone line.
Although DC stands for "direct current" DC often refers to "constant polarity" Under this definition DC voltages can vary in time as seen in the raw output of a rectifier or the fluctuating voice signal on a telephone line