Electric Discharge Lamp – Definition, Types, Advantages, Disadvantages & Applications

Electric Discharge Lamps

A lighting device consisting of a transparent container within which a gas is energized by applying an electric voltage and thereby made to glow is known as electric discharge lamp. The electric discharge lamp is also known as vapor lamp or gas-discharge lamp.

Actually, the electric discharge lamp is family of artificial light sources that generates light by sending an electric discharge through an ionized gas. In all types of electric discharge lamps, an electric current is passed through a gas or vapor which renders it luminous. The most commonly used elements in these types of lamps are neon, mercury and sodium vapors.

The color of the light produced by the electric discharge lamp depends on the nature of gas or vapor used in the lamp, such as −

• Orange-red light - Neon discharge field

• Orange-yellow light - Sodium vapor light

• Always bluish light - Mercury vapor lamp

Types of Electric Discharge Lamps

Based on the method of production of light in the lamp, the electric discharge lamps are classified into following two types −

Type-1

The type-1 is the category of electric discharge lamps in which the color of light is the same as produced by the electric discharge through the gas or vapor. Some of these lamps are −

• Sodium Vapor Lamp

• Mercury Vapor Lamp

• Neon Gas Lamp

Type-2

This category involves those discharge lamps which use the phenomenon of fluorescence. For this reason, they are also known as fluorescent lamps.

In these types of lamps, the electric discharge through the gas or vapor produces ultra-violet rays which cause fluorescence in certain materials (called as phosphor). The inner surface of the fluorescent lamp is coated with a phosphor material which absorbs the invisible UV rays and emits visible rays. Fluorescent mercury vapor lamp is an example of this type of electric discharge lamps.

Advantages of Electric Discharge Lamps

The advantages of electric discharge lamps are as follows −

• Electric discharge lamps have longer life.

• There operating cost is low.

• Electric discharge lamps can be designed for different colors.

• Electric discharge lamps produce less heat.

• They can be used for a number of applications.

Disadvantage of Electric Discharge Lamps

Electric discharge lamps have the following disadvantages −

• Initial cost of electric discharge lamps is high.

• Electric discharge lamps are suitable for a particular position.

• They require some starting mean like starter or starting transformer.

• In case electric discharge lamps, the flicker causes the stroboscopic effect.

• They require some time to attain full brilliancy.

• Electric discharge lamps have poor power factor.

Applications of Electric Discharge Lamps

Electric discharge lamps find applications in the following fields −

• They are widely used in street lighting.

• Used in aircrafts.

• These lamps are also used in sport arenas.

• Electric discharge lamps are used in gymnasiums and many industries.