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:
“A positive learning climate in a school for young children is a composite of many things. It is an attitude that respects children. It is a place where children receive guidance and encouragement from the responsible adults around them. It is an environment where children can experiment and try out new ideas without fear of failure. It is an atmosphere that builds children’s self-confidence so they dare to take risks. It is an environment that nurtures a love of learning.”
—Carol B. Hillman (20th century)
“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)