The incandescent lamp is the oldest and most common type of lamp. Light is emitted when electricity flows through and heats a tungsten filament. Incandescent lamps have a low efficacy compared to other lighting options and a short average operating life.
The three most common types of incandescent lamps:
• Standard incandescent lamps
• Tungsten halogen lamps
• Reflector lamps
Halogen lamps are a special type of incandescent lamp in which the gas contained within the bulb prevents the vaporized material of the tungsten filament from depositing on the surface of the bulb and forces re-deposition on the filament. This phenomenon slows the deterioration of the filament, improves the quality of the light emitted and increases the life of the lamp. The electrical behaviour of these lamps is the same as that of incandescent lamps.