Electric light

An electric light, lamp, or light bulb is a device that turns electricity into light. It is the most widespread type of artificial lighting. The three main kinds are incandescent lamps, which heat a filament until it glows; gas-discharge lamps, like fluorescents, which create light through an electric arc in a gas; and LED lamps, which use electron flow across a semiconductor band gap. Modern electric lights come in many shapes and sizes for different uses, and most run on power from a central grid.

Before electric lighting became common in the early 1900s, people relied on candles, gas lights, oil lamps, and fires. In 1799–1800, Alessandro Volta built the first electric battery, the voltaic pile. Current from these batteries could make copper wire glow white-hot. Vasily Vladimirovich Petrov created the first lasting electric arc in 1802, and English chemist Humphry Davy showed a working arc light in 1806. It took over a century of steady improvements, many designs, patents, and legal fights to get from those early experiments to commercially made incandescent bulbs in the 1920s.

In 1840, Warren de la Rue put a platinum coil inside a vacuum tube and ran current through it, making one of the first electric light bulbs. The idea was that platinum’s high melting point would let it work at high temperatures, and the vacuum would limit reactions with gas, making it last longer. Though efficient, platinum was too costly for commercial use. English inventor William Greener contributed to early electric lighting with his 1846 lamp, which set the stage for later advances like Thomas Edison’s.

The late 1870s and 1880s saw fierce competition and invention. Joseph Swan in the UK and Thomas Edison in the US each developed working incandescent lamps on their own. Swan’s bulbs, based on William Staite’s designs, worked but had filaments that were too thick. Edison focused on thinner filaments and better vacuums, creating a more practical bulb. Their rivalry ended in a merger, forming the Edison and Swan Electric Light Company, which sold lamps with a new filament by Swan. By the early 1900s, these bulbs had fully replaced arc lamps.

Around the turn of the century, bulb life and efficiency improved, especially with William D. Coolidge’s tungsten filament, patented in 1912. This became the standard for incandescent bulbs for many years. In 1910, Georges Claude introduced the first neon light, leading to neon signs in advertising. In 1934, physicist Arthur Compton told GE’s lamp department about successful fluorescent lighting tests in Great Britain. Spurred by this, a team led by George E. Inman built a prototype fluorescent lamp that year at GE’s Nela Park lab. This required much trial and error with lamp sizes, cathode designs, gas pressures, and phosphor coatings before the product was ready.

The first practical LED arrived in 1962, but these early ones were inefficient and only showed deep red, limiting them to numeric displays and indicator lights. In 1994, Shuji Nakamura of Nichia Corporation demonstrated the first high-brightness blue LED. This led to the first white LED, which used a phosphor coating to turn some blue light into lower frequencies, creating white light. By the early 2000s, LED lamps for general lighting were on the market, and in 2009 Philips introduced the first bulbs meant to replace standard 60-watt Edison screw fixtures.

A worldwide phase-out of incandescent bulbs began in the early 21st century, driven by government rules and consumer demand for higher efficiency and longer life. By 2019, U.S. electricity use had dropped for five straight years, partly because people switched from incandescent bulbs to LEDs.