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
Royal Society of London Michael Faraday Prize winner is required to present a lecture as part of the Society's annual programme of public events, which is usually held in January of the following year; during the lecture, the President of the Royal Society awards the medal. Unlike other prizes awarded by the society, the committee has not always publicly provided a rationale. This has occurred five times—in 2004 to Martin Rees, in 2006 to Richard Fortey, in 2007 to Jim Al-Khalili, in 2008 to John D. Barrow and most recently in 2009 to Marcus du Sautoy. Royal Society of London Michael Faraday Prize The Royal Society of