Incandescent Light Bulb

Incandescent light bulb popularly known as incandescent light globe or incandescent lamp is just an electric light used to generate light energy. Production of light takes place with a tungsten filament heated by the electric current passing through it. A quartz or glass bulb is used to protect the filament from oxidation.  Also, the bulb is filled with inert gas. Today, Incandescent light bulbs come in variety of sizes, ratings and output. Although, these bulbs are less efficient than other types of electric lights like CFL, LED lights, fluorescent lamps etc., even now they are not considered to be just a device to produce light but an element of comfort and design.

Construction of Incandescent Light Bulb

The incandescent light bulb was invented by Thomas Edison in 1879. It has  a very simple structure. Here base of the bulb has metal contacts and they are connected to the ends of the circuit. Metal contacts in turn are connected to wires attached to the filament. The tungsten filament lies in the center of the incandescent bulb with the help of a glass mount. Bulb of quartz or glass encloses the filaments, wires and inert gases like argon and nitrogen. When the incandescent bulb is given a power supply, current flows through the filaments and wires from contact to contact and the bulb glows. This is because of the excitation of atoms inside and zip of the tiny particles through the filament causing atoms to give energy in the form of heat and light. Filament of the bulb is made of tungsten. The tungsten is made into a double coil to fit it to a small space. Most of the incandescent light bulbs use tungsten based filaments.

                                      Construction of Incandescent Light Bulb

Major Types of Incandescent Light Bulbs

  • Standard Incandescent Light Bulbs

Commonly used in homes as a light source. It produces the required light just by heating the coil by electric current. Also known as screw-in "A"-type lamp.

  • Energy-saving incandescent light bulbs

This is a simple type of incandescent light bulb having a capsule which consists a halogen gas around the tungsten filament. This is used to increase the efficiency of the bulb. High cost is the major disadvantage, but in terms of efficiency it’s excellent. An inner coating in the bulb will reflect the heat to the capsule and helps in recycling the wasted heat energy.

  • Reflector Lamps

Reflector Lamps spread and direct light. Used for floodlighting, spotlighting, and down lighting applications both indoor and outdoor.

Incandescent Light Bulb Shapes

They come in variety of sizes and shapes. Each light bulb is designated by a letter which is then followed by a number. Letter represents the shape of the bulb; number represents the diameter in eighths of an inch.

                                            Incandescent Light Bulb Shapes

Advantages & Disadvantages of Incandescent Light Bulbs


  • Good for lighting small areas.
  • Cheap for the consumer.
  • No toxic materials are present.
  • Safe to handle.
  • Fast on time.
  • No flicker.


  • Not energy Efficient.
  • Not good for large areas.
  • Low lifespan compared to other light bulbs.


The below table shows a comparison between different light bulbs used commonly. LED light is the most energy efficient light bulb with high price. They have huge lifespan and use less amount of energy only. Compact Fluorescent Light Bulbs also uses very little heat and also they are efficient than incandescent light bulbs. Next is the Halogen bulb which is the improved version of the incandescent ones.


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