various sources of white light and their wokring

8/10/2019 Various Sources of white Light and Their Wokring

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Description of various white light emitting

sources.

Incandescent lamp

An incandescent light bulb is an electric lightwhich produces light with a

wire flamentmade o tungsten (or earlier, carbon) heated to a high temperature

by an electric current passing through it, until it glows. The hot flament is

protected rom oxidation within a glass or quartz bulb enclosure that is flled with

inert gas or eacuated. The bulb is flled with an inert gassuch as argon(!"#)

and nitrogen($#) to reduce eaporationo the flament and preent

its oxidationat a pressure o about $% &'a. A %% light bulb or *% +

operation emits about ,$%% lumens, about 17 lumens/W. ncandescent lampsare relatiely inexpensie to ma&e. The typical liespan o an A- incandescent

lamp is $% to ,%%% hours.

ncandescent bulbs are manuactured in a wide range o sizes, light output,

and oltageratings, rom . olts to about "%% olts. They require no external

regulating equipment, have lowmanuacturing costs,and wor equall!

well on either alternating current or direct current.

ncandescent bulbs are much less e"cientthan most other types o electric

lighting/ incandescent bulbs conert less than # o the energy they use into

isible lightwith the remaining energy being conerted into heat.

The luminous e0cacyo a typical incandescent bulb is 1# lumens per watt,

compared to the 1% lm2 o a compact 3uorescentbulb. ncandescent bulbs

typically hae short lietimes compared with other types o lighting/ around

1,$$$ hoursor home light bulbs ersus typically %,%%% hours or compact

3uorescents and "%,%%% hours or lighting 456s. ncandescent bulbs are

gradually being replaced in many applications by other types o electric light,

such as 3uorescent lamps, compact 3uorescent lamps (-74), cold cathode3uorescent lamps(--74), high8intensity discharge lamps, and light8emitting

diode lamps(456)

9ost light bulbs hae either clear or coated glass. The coated glass bulbs hae a

white powdery substance on the inside called &aolinwhich is a white, chal&y clay

in a ery fne powder orm, that is deposited on the interior o the bulb. t
http://en.wikipedia.org/wiki/Electric_lighthttp://en.wikipedia.org/wiki/Incandescent_light_bulb#Filamenthttp://en.wikipedia.org/wiki/Inert_gashttp://en.wikipedia.org/wiki/Argonhttp://en.wikipedia.org/wiki/Nitrogenhttp://en.wikipedia.org/wiki/Evaporationhttp://en.wikipedia.org/wiki/Oxidationhttp://en.wikipedia.org/wiki/Voltagehttp://en.wikipedia.org/wiki/Manufacturing_costhttp://en.wikipedia.org/wiki/Luminous_efficacyhttp://en.wikipedia.org/wiki/Compact_fluorescent_lamphttp://en.wikipedia.org/wiki/Fluorescent_lamphttp://en.wikipedia.org/wiki/Cold_cathodehttp://en.wikipedia.org/wiki/Cold_cathodehttp://en.wikipedia.org/wiki/High-intensity_discharge_lamphttp://en.wikipedia.org/wiki/LED_lamphttp://en.wikipedia.org/wiki/LED_lamphttp://en.wikipedia.org/wiki/Kaolinhttp://en.wikipedia.org/wiki/Incandescent_light_bulb#Filamenthttp://en.wikipedia.org/wiki/Inert_gashttp://en.wikipedia.org/wiki/Argonhttp://en.wikipedia.org/wiki/Nitrogenhttp://en.wikipedia.org/wiki/Evaporationhttp://en.wikipedia.org/wiki/Oxidationhttp://en.wikipedia.org/wiki/Voltagehttp://en.wikipedia.org/wiki/Manufacturing_costhttp://en.wikipedia.org/wiki/Luminous_efficacyhttp://en.wikipedia.org/wiki/Compact_fluorescent_lamphttp://en.wikipedia.org/wiki/Fluorescent_lamphttp://en.wikipedia.org/wiki/Cold_cathodehttp://en.wikipedia.org/wiki/Cold_cathodehttp://en.wikipedia.org/wiki/High-intensity_discharge_lamphttp://en.wikipedia.org/wiki/LED_lamphttp://en.wikipedia.org/wiki/LED_lamphttp://en.wikipedia.org/wiki/Kaolinhttp://en.wikipedia.org/wiki/Electric_light


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di:uses the light emitted rom the flament, producing a gentler and eenly

distributed light.

%alogen lamp

A halogen lamp is an incandescent lampthat has a small amount o

a halogensuch as iodineor bromineadded. The combination o the halogen gas

and the tungstenflament produces a halogen c!clechemical reaction which

redeposits eaporated tungsten bac& onto the flament, increasing its lie.

;ecause o this, a halogen lamp can be operated at a higher temperature than a

standard gas8flled lamp o similar power and lietime, producing light o a

higher luminous e0cacy.

&luorescent 'amp

A (uorescent lampor a 3uorescent tube is a low pressure mercury8apor gas8

discharge lamp that uses 3uorescence to produce isible light. An electric

current in the gas excites mercury apor which produces short8wae
http://en.wikipedia.org/wiki/Incandescent_light_bulbhttp://en.wikipedia.org/wiki/Halogenhttp://en.wikipedia.org/wiki/Iodinehttp://en.wikipedia.org/wiki/Brominehttp://en.wikipedia.org/wiki/Tungstenhttp://en.wikipedia.org/wiki/Luminous_efficacyhttp://en.wikipedia.org/wiki/Incandescent_light_bulbhttp://en.wikipedia.org/wiki/Halogenhttp://en.wikipedia.org/wiki/Iodinehttp://en.wikipedia.org/wiki/Brominehttp://en.wikipedia.org/wiki/Tungstenhttp://en.wikipedia.org/wiki/Luminous_efficacy


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ultraiolet light that then causes a phosphor coating on the inside o the bulb to

glow.

-onentional linear 3uorescent lamps hae life spans around )$,$$$ and

*$,$$$ hours.

hen light is turned on, the electric power heats up the cathode resulting in

thermionic emission. The emitted electrons collide with and ionize the gasatoms

inside the bulb surrounding the flament. the incident ree electron has

enough &inetic energy, it transers energy to the atomg, these photons hae waelengthsin the ultraiolet(?+)

region o the spectrum (*".$ and @ nm). These are then conerted to isible

range by ma&ing use o 3uorescence. 4ight8emitting phosphors are applied as a

paint8li&e coating to the inside o the tube. This coating absorbs the ultraiolet

photons, causing a similar =ump and drop process, with emission o a urther

photon. The photon that is emitted rom this second interaction has a lower

energy than the one that caused it and lies in isible region. The di:erence in

energy between the absorbed ultra8iolet photon and the emitted isible light

photon goes toward heating up the phosphor coating.

7luorescent lamps must use an auxiliary deice, a ballast, to regulate the

current 3ow through the lamp. >igher quality 3uorescent lamps use either a

higher - halophosphate coating, or a triphosphormixture, based

on europiumand terbiumions, that hae emission bands more eenlydistributed oer the spectrum o isible light

%igh+intensit! discharge lamp

%igh+intensit! discharge lamps(%ID lamps) are a type o electricalgas8

discharge lampwhich produces light by means o an electric arc

between tungstenelectrodeshoused inside a translucent or transparent used

quartzor used aluminaarc tube. This tube is flled with

both gasand metalsalts. The gas acilitates the arcigh8intensity discharge lamps are a type o arc lamp
http://en.wikipedia.org/wiki/Thermionic_emissionhttp://en.wikipedia.org/wiki/Noble_gashttp://en.wikipedia.org/wiki/Kinetic_energyhttp://en.wikipedia.org/wiki/Energy_levelhttp://en.wikipedia.org/wiki/Wavelengthhttp://en.wikipedia.org/wiki/Ultraviolethttp://en.wikipedia.org/wiki/Fluorescencehttp://en.wikipedia.org/wiki/Electrical_ballasthttp://en.wikipedia.org/wiki/Europiumhttp://en.wikipedia.org/wiki/Terbiumhttp://en.wikipedia.org/wiki/Electric_lighthttp://en.wikipedia.org/wiki/Gas-discharge_lamphttp://en.wikipedia.org/wiki/Gas-discharge_lamphttp://en.wikipedia.org/wiki/Tungstenhttp://en.wikipedia.org/wiki/Electrodehttp://en.wikipedia.org/wiki/Fused_quartzhttp://en.wikipedia.org/wiki/Fused_quartzhttp://en.wikipedia.org/wiki/Aluminahttp://en.wikipedia.org/wiki/Gashttp://en.wikipedia.org/wiki/Metalhttp://en.wikipedia.org/wiki/Plasma_(physics)http://en.wikipedia.org/wiki/Arc_lamphttp://en.wikipedia.org/wiki/Thermionic_emissionhttp://en.wikipedia.org/wiki/Noble_gashttp://en.wikipedia.org/wiki/Kinetic_energyhttp://en.wikipedia.org/wiki/Energy_levelhttp://en.wikipedia.org/wiki/Wavelengthhttp://en.wikipedia.org/wiki/Ultraviolethttp://en.wikipedia.org/wiki/Fluorescencehttp://en.wikipedia.org/wiki/Electrical_ballasthttp://en.wikipedia.org/wiki/Europiumhttp://en.wikipedia.org/wiki/Terbiumhttp://en.wikipedia.org/wiki/Electric_lighthttp://en.wikipedia.org/wiki/Gas-discharge_lamphttp://en.wikipedia.org/wiki/Gas-discharge_lamphttp://en.wikipedia.org/wiki/Tungstenhttp://en.wikipedia.org/wiki/Electrodehttp://en.wikipedia.org/wiki/Fused_quartzhttp://en.wikipedia.org/wiki/Fused_quartzhttp://en.wikipedia.org/wiki/Aluminahttp://en.wikipedia.org/wiki/Gashttp://en.wikipedia.org/wiki/Metalhttp://en.wikipedia.org/wiki/Plasma_(physics)http://en.wikipedia.org/wiki/Arc_lamp


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>igh8intensity discharge lamps ma&e more isible light per unit o electric power

consumedthan 3uorescentand incandescentlamps since a greater proportion o

their radiation is isible light in contrast to inrared.

'D lamp

An 'D - light8emitting diode)lamphae a liespan and electrical e0ciencythatis seeral times better than incandescent lamps, and signifcantly better thanmost 3uorescent lamps, with some chips able to emit more than 1$$ lumensper watt.

4i&e incandescent lamps and unli&e most 3uorescent, 456s come to fullbrightness without need for a warm+up time/ the lie o 3uorescent lightingis also reduced by requent switching on and o:. nitial cost o 456 is usuallyhigher. 6egradation o 456 dye and pac&aging materials reduces light output tosome extent oer time.

456s do not emit light in all directions, and their directional characteristics a:ectthe design o lamps. The light outputo single 456s is less than that oincandescent and compact 3uorescent lamps/ in most applications multiple 456sare used to orm a lamp.

456 chips need controlled direct current(6-) electrical power/ anappropriate circuitis required to conert alternating current rom the supply tothe regulated low oltage direct current used by the 456s. 456s are aderselya:ected by high temperature, so 456 lamps typically include heatdissipationelements such as heat sin&sand cooling fns.Ceneral8purpose lighting needs white light. 456s emit light in a ery narrowband o waelengths, emitting light o a color characteristic o theenergy bandgapo the semiconductormaterial used to ma&e the 456. To emitwhite light rom 456s requires mixing light rom red, green, and blue 456s, orusing a phosphorto conert some o the light to other colors.

ompact (uorescent lamp

A compact (uorescent lamp(&') is a 3uorescent lampthat uses a tube

which is cured or olded to ft into the space o an incandescent bulb, and a

compact electronic ballastin the base o the lamp.

Theyhae seeral small8diameter tubes =oined in a bundle o two, our, or six, or

a small diameter tube coiled into a helix, to proide a high amount o light

output in little olume. -ompact 3uorescent lampsare now aailable in the same
http://en.wikipedia.org/wiki/Luminous_efficacyhttp://en.wikipedia.org/wiki/Luminous_efficacyhttp://en.wikipedia.org/wiki/Fluorescent_lamphttp://en.wikipedia.org/wiki/Incandescent_light_bulbhttp://en.wikipedia.org/wiki/Light-emitting_diodehttp://en.wikipedia.org/wiki/Electrical_efficiencyhttp://en.wikipedia.org/wiki/Incandescent_light_bulbhttp://en.wikipedia.org/wiki/Fluorescent_lampshttp://en.wikipedia.org/wiki/Luminous_fluxhttp://en.wikipedia.org/wiki/Direct_currenthttp://en.wikipedia.org/wiki/LED_circuithttp://en.wikipedia.org/wiki/Thermal_management_of_high-power_LEDshttp://en.wikipedia.org/wiki/Thermal_management_of_high-power_LEDshttp://en.wikipedia.org/wiki/Heat_sinkhttp://en.wikipedia.org/wiki/Fin_(extended_surface)http://en.wikipedia.org/wiki/Bandgaphttp://en.wikipedia.org/wiki/Semiconductorhttp://en.wikipedia.org/wiki/Phosphorhttp://en.wikipedia.org/wiki/Fluorescent_lamphttp://en.wikipedia.org/wiki/Electronic_ballasthttp://en.wikipedia.org/wiki/Compact_fluorescent_lamphttp://en.wikipedia.org/wiki/Compact_fluorescent_lamphttp://en.wikipedia.org/wiki/Luminous_efficacyhttp://en.wikipedia.org/wiki/Luminous_efficacyhttp://en.wikipedia.org/wiki/Fluorescent_lamphttp://en.wikipedia.org/wiki/Incandescent_light_bulbhttp://en.wikipedia.org/wiki/Light-emitting_diodehttp://en.wikipedia.org/wiki/Electrical_efficiencyhttp://en.wikipedia.org/wiki/Incandescent_light_bulbhttp://en.wikipedia.org/wiki/Fluorescent_lampshttp://en.wikipedia.org/wiki/Luminous_fluxhttp://en.wikipedia.org/wiki/Direct_currenthttp://en.wikipedia.org/wiki/LED_circuithttp://en.wikipedia.org/wiki/Thermal_management_of_high-power_LEDshttp://en.wikipedia.org/wiki/Thermal_management_of_high-power_LEDshttp://en.wikipedia.org/wiki/Heat_sinkhttp://en.wikipedia.org/wiki/Fin_(extended_surface)http://en.wikipedia.org/wiki/Bandgaphttp://en.wikipedia.org/wiki/Semiconductorhttp://en.wikipedia.org/wiki/Phosphorhttp://en.wikipedia.org/wiki/Fluorescent_lamphttp://en.wikipedia.org/wiki/Electronic_ballasthttp://en.wikipedia.org/wiki/Compact_fluorescent_lamphttp://en.wikipedia.org/wiki/Compact_fluorescent_lamp


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popular sizes as incandescent and are used as an energy8saingalternatie in

homes. &'s use one+fth to one+third the electric power,and last eight to

fteen times longer as compared to incandescent lamps. A -74 has a higher

purchase price than an incandescent lamp, but can sae oer fe times its

purchase price in electricity costs oer the lamp

various sources of white light and their wokring

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