Electric light be made with a screw-thread base, two metal pins, two metal caps or a bayonet cap. The three main categories of electric lights are incandescent lamps, which produce light by a filament heated white-hot by electric current, gas-discharge lamps, which produce light by means of an electric arc through a gas, and LED lamps, which produce light by a flow of electrons across a band gap in a semiconductor. Before electric lighting became common in the early 20th century, people used candles, gas lights, oil lamps, and fires. Cornish chemist Humphry Davy developed the first incandescent light in 1802, followed
Light Years, The Very Best of Electric Light Orchestra Light Years, The Very Best of Electric Light Orchestra Light Years, The Very Best of Electric Light Orchestra is a two CD compilation album by Electric Light Orchestra (ELO). The album celebrates the band's 25th Anniversary singles career starting in 1972 and contains all of ELO's 29 UK hit singles plus other single edits that either didn't chart or were hits in other countries. All the songs included are the edited 7" single versions. It is also the first ELO compilation to feature the song "Across the Border" which was scheduled to be released as an EP track in 1980