Presenting

By

A.S.Krishna

Incandescentlight

bulb

An incandescent light bulb, incandescent lamp or incandescent light globe is an electric light which produces light with a wire filament heated to a high temperature by an electric current passing through it, until it glows (see Incandescence).

The hot filament is protected from oxidation with a glass or quartz bulb that is filled with inert gas.

Most bulbs are used in a socket which provides mechanical support and electrical connections.

Introduction

Incandescence is the emission of electromagnetic radiation (including visible light) from a hot body as a result of its temperature.

The term derives from the Latin verb incandescere, to glow white.

It is a special case of thermal radiation.

Incandescence is exploited in incandescent light bulbs.

Sunlight is the incandescence of the "white hot" surface of the sun.

What is Incandescent

HumphryDavyIn 1802

In 1850, Davy created the first incandescent light by passing the current through a thin strip of platinum, chosen because the metal had an extremely high melting point.But it was not bright enough nor did it last long enough to be practical.Over the first three-quarters of the 19th century many experimenters worked with various combinations of platinum or iridium wires, carbon rods, and evacuated or semi-evacuated enclosures.

Flash Back

Lindsay James Bowman In 1835

Warren de la Ruein 1840

Frederick de Moleynsin 1841

John Wellington Starrin 1845

Jean Eugène Robert-Houdinin 1851

Alexander Lodyginin 1872

Heinrich Göbelin 1893

Henry Woodward

Joseph Wilson Swanin 1879

Thomas Alva Edisonin 1879

In addressing the question of who invented the incandescent lamp, historians Robert Friedel and Paul Israel list 22 inventors of incandescent lamps prior to Joseph Swan and Thomas Edison.

They conclude that Edison's version was able to outstrip the others because of a combination of three factors..

That three factors are shown in next slide…………

Flash Back

An effective incandescent material

A higher vacuum than others and

A high resistance that made power distribution from a centralized source economically viable.

Three Factors

Of the power consumed by typical incandescent light bulbs, 95% or more is converted into heat rather than visible light.

Incandescent bulbs are much less efficient than most other types of electric lighting.

Incandescent bulbs are much less efficient than most other types of electric lighting.

The initial cost of an incandescent bulb is small compared to the cost of the energy it uses over its lifetime.

Remains

1. Outline of Glass bulb2.Low pressure inert gas (argon, nitrogen, krypton, xenon)3.Tungsten filament4.Contact wire (goes out of stem)5.Contact wire (goes into stem)6.Support wires (one end embedded in stem; conduct no current)7.Stem (glass mount)8.Contact wire (goes out of stem)9.Cap (sleeve)10.Insulation (vitrite)11.Electrical contact

They require no external regulating equipment, have low manufacturing costs, and work equally well on either alternating current or direct current.

As a result, the incandescent lamp is widely used in household and commercial lighting, for portable lighting such as table lamps, car headlamps, and flashlights, and for decorative and advertising lighting.

Applications

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