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
Inert gas carbon dioxide. (Listed as many different names depending on the gas supplier). In underwater diving an inert gas is a component of the breathing mixture which is not metabolically active, and serves to dilute the gas mixture. The inert gas may have effects on the diver, but these are thought to be mostly physical effects, such as tissue damage caused by bubbles in decompression sickness. The most common inert gas used in breathing gas for commercial diving is helium. Inert gas An inert gas/noble gas is a gas which does not undergo chemical reactions under a set of given conditions.