Electrical lights or electrical bulb is a device that produces visible light which is produce by the help of direct or alternating electrical current. It is the most famous form of artificial lighting and is becoming an essential commodity in the modern day society.

History of electrical lights:

  • Artificial lighting began a thousands of years ago, and has been refined constantly to the present day.
  • Starting from control of fire by early life and later evolving it to use it in oil lamps and candles.
  • Furthermore, in the late 17th CE, scientists started experimenting with gas lighting and produced he first light gas.
  • In early 1800’s, the arc lamp was invented followed by the first electrical lamp over 10,000 lumens.
  • In the mid 1800’s Thomas Edison produced a 16-watt that lasted 1500 hours.
  • It continued to evolve until 2008 where Ushio Lighting demonstrated the first LED filament.
  • In 2011, Philips, won the L Prize for LED screw-lamp which was equivalent to 60 watt incandescent lamp for general use.

Parts in an electrical lamp:

  • Lamp is a replaceable component that produces light from electrical current.
  • Lamps are usually made of metal, ceramic, glass and plastic which secures the lamp in the socket of the light fixture.
  • The electrical connection to the socket is usually made with a screw-thread base, two metal caps and pins. A bayonet cap can be replaced for a metal cap.
  • The part which produces light is called a filament. It turns white-hot when electrical current is passed though it and that is the part which emits the light.
  • Gas discharged lamps produce light by means of an electrical arc through gas.
  • LED lamps produce light by flow of electrons across a space in a semi-conductor.

Types of lights:

  1. Incandescent light bulb:

It consists of a heated filament inside a glass envelope and emits continuous light. It has a lifetime of 2 to 20,000 hours.

  1. Halogen lamp:

These are incandescent lamps that use a fuse quartz envelope filled with only halogen lamp. Its optical spectrum is continuous and has a lifetime of 3000 to 6000 hours.

  1. Fluorescent lamp:

It has a mercury line and phosphor as its optical spectrum. It has a lifetime of 8000 to 20000 hours. It is available in different colours according to the temperatures.

  1. Metal halide lamp:

They have a Quasi-continuous optical spectrum and works for 6000 to 20000 hours. They emit a cold white colour.

  1. Sulphur lamp:

It has a continuous optical spectrum and has a lifetime of 15000 to 20000 hours but emits a pale green colour light only.

  1. LED lamp:

It has a narrow line optical spectrum and can be used for 18000 to 20000 hours. Another advantage is that it emits various colours according to the temperatures.