what are the balls in power lines for
Balisor High voltage power cables, particularly those close to airports, need to be visible day and night. During the day, brightly coloured balls positioned along the length of the cables are sufficient, but during the night, lighting is necessary. These beacons provide this lighting by glowing red, the standard colour used in aviation for warning beacons.
Basketball court The key, free throw lane or shaded lane refers to the usually painted area beneath the basket; for the NBA it is 16 feet (4.9 m) wide, for the NCAA it is 12 feet (3.7 m) wide; for both instances it extends 15 feet (4.6 m) from the backboard. At the top of the rectangle is the free throw line, behind which players shoot uncontested shots when they're fouled. A circle is drawn around the free-throw line with a 6 feet (1.8 m) radius; this is used for jump ball instances, as is done at the center circle. Two 6-inch hash lines, 3 ft from the free throw lane line and 5 ft 8 in from the free throw line, show the lower defensive box linked to the restricted area.