UPSC 2014 CDS I GK Paper

When an incandescent electric bulb glows, the electric energy is partly converted into light energy and partly into heat energy. The incandescent light bulb turns electricity into light by sending the electric current through a thin wire called a filament. Filaments are made up mostly of tungsten, ametal. The resistance of the filament heats the bulb up. Eventually the filament gets so hot that it glows, producing light.