Electric light





Most of the industrialized world is lit by electric lights, which are used
both at night and to provide additional light during the daytime. These
lights are normally powered by the electric grid, but some run on local
generators, and emergency generators serve as backups in hospitals and other
locations where a loss of power could be catastrophic. Battery-powered
lights, usually called "flashlights" or "torches", are used for portability
and as backups when the main lights fail.

Types of electric lighting include:

   * incandescent light bulbs
   * arc lamps
   * fluorescent lights, e.g., neon lamps
   * microwave pumped [?]
   * lasers
   * LEDs
   * OLEDs

The total amount of artificial light is sufficient for cities to be easily
visible from the air at night.