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
Edison and Swan Electric Light Company 1964, AEI merged its lamp and radio valve manufacturing interests with those of Thorn Electrical Industries to form British Lighting Industries Ltd. Edison Swan (or later Siemens Edison Swan) produced a wide range of vacuum tubes and cathode ray tubes under the names "Ediswan" or "Mazda" and the 1964 Mazda Valve Data Book claimed: "Professor Sir. Ambrose Fleming... was Technical Consultant to the Edison Swan Company at the time. It was this close co-operation between University and Factory which resulted in the first radio valve in the world." Edison and Swan Electric Light Company The Edison and Swan Electric Light