Comparison of Different Light Sources

In this article, we will compare and contrast the various features of different types of light sources such as incandescent lamps, fluorescent lamps, sodium vapor lamps and mercury vapor lamps.

Starting and Stopping

• Incandescent lamps have instantaneous start and they become momentarily off when the power supply cuts off.

• Fluorescent lamps have a reaction time of one second or a little more at the start. These lamps go off and restart when the power supply is restored.

• Sodium vapor lamps have a starting time of 5 to 8 minutes. These lamps turn off, when the supply goes off and cannot be restarted after the recovery of the supply voltage tills its value falls to the normal value.

• Mercury vapor lamps also take 5 to 8 minutes for starting. These lamps turn off and cannot be restarted after the recovery of the supply voltage till its value falls to the normal.

Color of Light Emitted

• Incandescent lamps produce light of color very near to the natural color.

• For the fluorescent lamps, the color of the light produced varies with the phosphor coating.

• Sodium vapor lamps produce light of yellowish color. These lamps suffer from color distortion.

• Mercury vapor lamps suffer from color distortion.

Average Life

• The average life an incandescent lamp is around 1000 hours.

• For the fluorescent lamps, the average life is high, approximately 4000 hours.

• Sodium vapor lamps have average life around 3000 hours.

• The average life of mercury vapor lamps is also 3000 hours.

Installation Cost

• The installation cost of the incandescent lamps is minimum among all the types of lamps.

• Fluorescent lamps have maximum installation cost.

• For the sodium vapor lamps, the installation cost is high. Although it is less than that of incandescent lamps, but more than that of fluorescent lamps.

• The installation cost of mercury vapor lamps is high, but less than that of fluorescent lamps.

Operating Cost

• The incandescent lamps have maximum operating cost.

• The operating cost is minimum for the fluorescent lamps.

• Sodium vapor lamps have operating cost lesser than the incandescent lamps but higher than the fluorescent lamps.

• For the mercury vapor lamps, the operating cost is much less than that of incandescent lamps but more than that of fluorescent lamps.

Stroboscopic Effect

• Incandescent lamps do not suffer from stroboscopic effect.

• Stroboscopic effect is present in fluorescent lamps, sodium vapor lamps, and mercury vapour lamps.

Applications

• Incandescent lamps are widely used in automobiles, trains, aeroplanes, domestic, industrial and street lightings, etc.

• Fluorescent lamps are used for lighting in domestic, industrial, commercial, semi-direct lighting, etc.

• Sodium vapor lamps are suitable for street lighting.

• Mercury vapor lamps are very suitable for open space like, parks, roads, highway lightings, etc.