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 is to reduce consumer concerns about efficient light bulbs due to variable quality of products. Those CFLs with a recent Energy Star certification start in less than one second and do not flicker. Energy Star Light Bulbs for Consumers is a resource for finding and comparing Energy Star qualified lamps. In 2011, Republican House members introduced a Better Use of Light Bulbs Act or BULB Act (H.R. 91), which would have repealed Subtitle B of Title III of the Energy Independence and Security Act of 2007. H.R. 2417 failed to pass in the U.S. House. On 16 December 2011, the