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:
“As for the terms good and bad, they indicate no positive quality in things regarded in themselves, but are merely modes of thinking, or notions which we form from the comparison of things with one another. Thus one and the same thing can be at the same time good, bad, and indifferent. For instance music is good for him that is melancholy, bad for him who mourns; for him who is deaf, it is neither good nor bad.”
—Baruch (Benedict)
“There is no reason why parents who work hard at a job to support a family, who nurture children during the hours at home, and who have searched for and selected the best [daycare] arrangement possible for their children need to feel anxious and guilty. It almost seems as if our culture wants parents to experience these negative feelings.”
—Gwen Morgan (20th century)