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 it forms a benchmark. Brent blend is a light crude oil (LCO), though not as light as West Texas Intermediate (WTI). It contains approximately 0.37% of sulphur, classifying it as sweet crude, yet not as sweet as WTI. Brent is suitable for production of petrol and middle distillates. It is typically refined in Northwest Europe. Brent Crude has an API gravity of approximately 38.06 which is equivalent to a specific gravity of 0.835. The ICE Futures Europe symbol for Brent crude futures is B. It was originally traded on the open outcry International Petroleum Exchange in London, but since 2005