Positive and Negative
In DC circuits, the positive pole is usually marked red (or "+") and the negative pole is usually marked black (or "-"), but other color schemes are sometimes used in automotive and telecommunications systems. On a car battery, the positive pole usually has a larger diameter than the negative pole.
In AC systems which are at no point connected to earth (unlike domestic mains wiring where the neutral is commonly earthed at substations and generators) polarity is not important as the two wires alternate polarity many times per second.
Read more about this topic: Electrical Polarity
Famous quotes containing the words positive and/or negative:
“I have always had something to live besides a personal life. And I suspected very early that to live merely in an experience of, in an expression of, in a positive delight in the human cliches could be no business of mine.”
—Margaret Anderson (1886–1973)
“Most literature on the culture of adolescence focuses on peer pressure as a negative force. Warnings about the “wrong crowd” read like tornado alerts in parent manuals. . . . It is a relative term that means different things in different places. In Fort Wayne, for example, the wrong crowd meant hanging out with liberal Democrats. In Connecticut, it meant kids who weren’t planning to get a Ph.D. from Yale.”
—Mary Kay Blakely (20th century)