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
Out of the Blue (Electric Light Orchestra album) Out of the Blue (Electric Light Orchestra album) Out of the Blue is the seventh studio album by the British rock group Electric Light Orchestra (ELO), released in October 1977. Written and produced by ELO frontman Jeff Lynne, the double album is among the most commercially successful records in the group's history, selling about 10 million copies worldwide. Jeff Lynne wrote the entire album in three and a half weeks after a sudden burst of creativity while hidden away in his rented chalet in the Swiss Alps. It took a further two months to record in Munich. Side three of