During ordinary operation, the tungsten of the filament evaporates; hotter, more-efficient filaments evaporate faster. Because of this, the lifetime of a filament lamp is a trade-off between efficiency and longevity. The trade-off is typically set to provide a lifetime of several hundred to 2,000 hours for lamps used for general illumination. Theatrical, photographic, and projection lamps may have a useful life of only a few hours, trading life expectancy for high output in a compact form. Long-life general service lamps have lower efficiency but are used where the cost of changing the lamp is high compared to the value of energy used.
During ordinary operation , the tungsten of the filament evaporates ; hotter , more - efficient filaments evaporate faster . Because of this , the lifetime of a filament lamp is a trade - off between efficiency and longevity . The trade - off is typically set to provide a lifetime of several hundred to 2,000 hours for lamps used for general illumination . Theatrical , photographic , and projection lamps may have a useful life of only a few hours , trading life expectancy for high output in a compact form . Long - life general service lamps have lower efficiency but are used where the cost of changing the lamp is high compared to the value of energy used .
Which types of lamps may have particularly short lives?
Which types of lamps may have particularly short lives ?
Theatrical, photographic, and projection lamps
Theatrical, photographic, and projection lamps