Incandescent light bulb Small variations in resistivity along the filament cause "hot spots" to form at points of higher resistivity; a variation of diameter of only 1% will cause a 25% reduction in service life. These hot spots evaporate faster than the rest of the filament, which increases the resistance at that point—this creates a positive feedback that ends in the familiar tiny gap in an otherwise healthy-looking filament. Irving Langmuir found that an inert gas, instead of vacuum, would retard evaporation. General service incandescent light bulbs over about 25 watts in rating are now filled with a mixture of mostly argon and
Phase-out of incandescent light bulbs from broken bulbs may be overstated, and can be ameliorated by taking a few simple steps. No mercury is used in the manufacturing of LED lamps, a different technology replacement for incandescent lamps. In addition, LED lamps do not require warmup time in cold weather, and in fact, perform better in colder temperatures, making them an excellent choice for use in cold locations, such as refrigeration units. The initial cost of CFLs and LEDs are higher than that of incandescent light bulbs. Typically this extra cost is repaid in the long-term, as both use less energy and have longer operating