Incandescent light bulbs produce visible light when an electrical current runs through a tungsten filament, heating it to several thousand degrees Fahrenheit. CFL lights produce light when an electrical current is passed through two electrodes. Electricity reacts with mercury and argon gas within the bulb, and when photons hit the inner layer of the CFL, visible light is produced. LEDs emit light when electricity is drawn in an arc pattern between an anode and a cathode, which are types of electrodes. In anodes, currents pass from metallic to nonmetallic conductors, according to Dictionary.com. Cathodes pass currents from nonmetallic to metallic conductors.
Lumens are a universal measurement of a light output of a light source. According to OtherPower.com, LED bulbs are small and only emit around 17 lumens per watt of power. According to the same source, CFL bulbs typically produce around 45 lumens per watt of power while incandescent bulbs generally emit around 17 lumens.
Incandescent bulbs are perhaps the least efficient types of light bulbs on the market. An incandescent light bulb can be expected to last for around 750 hours before they begin rapidly degenerating, according to the "Great Internet Light Bulb Book." CFL bulbs can last for up to 7,500 hours, according to Buildings.com. LED bulbs are the most efficient light bulbs on the market, lasting up to 45,000 hours, according to Lunar Accents Design Corp.
Toxic elemental mercury is found in the construction of many different types of light bulbs, including all fluorescents, high-pressure sodium (HPS) bulbs and metal halide (MH) bulbs. HPS and MH bulbs are engineered to produce very high light outputs. A metal halide light bulb can contain well over 81 mg of mercury, according to Dark Sky Society. CFL bulbs typically contain around 5 mg of elemental mercury, according to Earth Easy. Inhaling certain amounts of elemental mercury can result in respiratory failure and death, according to the U.S. Environmental Protection Agency. Incandescent light bulbs as well as LED bulbs contain no traces of elemental mercury.
Fluorescent light bulbs are not easily dimmable because of current technological limitations. Incandescent bulbs are the cheapest type of light bulb on the market; consumers can purchase a 100-watt incandescent light bulb for as little as 50 cents, as of June 2010. CFL bulbs can cost up to $5 apiece. LEDs, which are even more expensive, are clustered to broaden their applications. An LED cluster bulb that fits into traditional light bulb outlets can cost up to $50.