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
Brent Crude price two thirds of the world's internationally traded crude oil supplies. Originally Brent Crude was produced from the Brent oilfield. The name "Brent" comes from the naming policy of Shell UK Exploration and Production, operating on behalf of ExxonMobil and Royal Dutch Shell, which originally named all of its fields after birds (in this case the brent goose). But it is also a backronym or mnemonic for the formation layers of the oil field: Broom, Rannoch, Etive, Ness and Tarbert. Petroleum production from Europe, Africa, and the Middle East flowing West tends to be priced relative to this oil, i.e.