Ballasts

Description: The ordinary filament bulb is the epitome of simplicity: hook it up to the power line and it produces light. However, it is not a good example either of energy efficiency (about 5% of consumed power is turned into light, the rest being wasted as heat), or of lifetime (about 1,000 hours). Other types of lamps, such as fluorescent tubes, have an efficiency of about 22% and a lifetime of approximately 10,000 hours. But these come at the cost of added complexity: a fluorescent lamp needs special conditions to light up and it would self-destroy if connected directly to the power line, so its fixture must include a special igniting circuit (starter) and a device to regulate (stabilize) current through the lamp: a ballast.