Why does a refrigerator light last so long?
The life of an incandescent bulb depends almost exclusively on how many hours its filament has been hot. Since the bulb in a refrigerator is only on for a few minutes a day, it lasts for many years.
The life of an incandescent bulb depends almost exclusively on how many hours its filament has been hot. Since the bulb in a refrigerator is only on for a few minutes a day, it lasts for many years.
Since turning an incandescent bulb on and off doesn’t shorten the life of its filament significantly, you do well to turn it off whenever possible. The same isn’t true of a fluorescent tube—turning it on ages its filaments significantly (due to sputtering processes) so you shouldn’t turn a fluorescent lamp off if you plan to restart it in less than about 1 minute.