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Electric lamps produce visible light from electric current. They were invented early in the nineteenth century, but broader commercial adoption came later in the twentieth century thanks to Thomas Edison’s company, Edison Electric Light Company.  Thomas Edison was not the first to develop a light bulb, but he succeeded in developing a practical and inexpensive design. His laboratory tested more than 3000 different designs before filing a patent. Edison succeeded not only because he developed a durable lamp, but also because he developed an entire range of technology supporting it, such as parallel circuits, underground electric distribution grids, fuses, plugs, and switches.  In an incandescent electric lamp, light is emitted by a very thin filament kept under vacuum or in a low-pressure mixture of inert gases, as even a small amount of oxygen would cause the filament to burn. This filament has a high electric resistance and, as an electric current flows through it, the filament heats up, becoming incandescent and glowing with the heat, producing light. Back in the nineteenth century, these filaments were made of carbon, and later tungsten filaments were used. Tungsten filaments are very thin, with less than 2 mils in diameter and tightly coiled to maximize the electric resistance. Inside a lamp, the tungsten filament burns at a temperature greater than 4400 degrees Fahrenheit causing the metal to slowly evaporate. Over time, the wire slowly gets thinner and more fragile until it breaks. A home filament lamp has an expected lifetime of around 1000 hours.  In a filament lamp, only around 5 to 10 percent of the electric energy is converted into light. Most is wasted in the form of heat. Recent LED lamps have 80 to 90 percent efficiency and can last 20 to 30000 hours.