light sources its advantages & disadvantages
TRANSCRIPT
LIGHT SOURCES ITS LIGHT SOURCES ITS ADVANTAGES & ADVANTAGES &
DISADVANTAGESDISADVANTAGES
OPTOM FASLU MUHAMMED
LIGHT SOURCESLIGHT SOURCES
Natural day lightNatural day light Electric light (artificial)Electric light (artificial)
NATURAL DAY LIGHTNATURAL DAY LIGHT Free of chargeFree of charge
Varies in quantity, colour, directions Varies in quantity, colour, directions (time of day, weather condition)(time of day, weather condition)
ELECTRIC LIGHTELECTRIC LIGHT It is constant & provided there is a It is constant & provided there is a
supply supply of electricityof electricity
LUMINOUS EFFICACYLUMINOUS EFFICACY Amount of light given by a lamp for Amount of light given by a lamp for
each watt of power consumed & is each watt of power consumed & is measured in (lumens/watt)measured in (lumens/watt)
Cannot normally operated directly Cannot normally operated directly from mains electricity supplyfrom mains electricity supply
COLOUR PROPERTIESCOLOUR PROPERTIES Related to the spectral composition Related to the spectral composition
of the emission of the emission
Include -colour rendering Include -colour rendering -colour appearance-colour appearance
COLOUR RENDERING COLOUR RENDERING
Describes the appearance of colours Describes the appearance of colours
LAMP LIFELAMP LIFE The term ‘life’ of an electric lamp can The term ‘life’ of an electric lamp can
have two different meaningshave two different meanings
-The time after which the lamp -The time after which the lamp ceases to operateceases to operate
-The time after which the light -The time after which the light
output is so reducedoutput is so reduced
TUNGSTENTUNGSTEN Operate by heating a tungsten Operate by heating a tungsten
filament filament
Filled with an inert gasFilled with an inert gas
ADVADV Immediate full light outputImmediate full light output
Lamps operate in all positionLamps operate in all position
Easy to control the lampEasy to control the lamp
DIS ADVDIS ADV Short lifeShort life
Sensitive to vibrationSensitive to vibration
Not used for colour matchingNot used for colour matching
TUNGSTEN HALOGENTUNGSTEN HALOGEN Filament lampFilament lamp
Filled with halogen compound gasFilled with halogen compound gas
ADVADV Higher luminous efficacyHigher luminous efficacy
Lamp life longerLamp life longer
Small & compact ideal for optometric Small & compact ideal for optometric instrumentsinstruments
DIS ADVDIS ADV Surface of the bulb is liable to Surface of the bulb is liable to
deteriorate deteriorate
if touched with the fingersif touched with the fingers
DISCHARGE LAMPSDISCHARGE LAMPS Utilize the ionization of gas to produce Utilize the ionization of gas to produce
light light - fluorescent (low pressure - fluorescent (low pressure
mercury) mercury) lampslamps
-compact fluorescent lamps -compact fluorescent lamps -high pressure mercury lamps-high pressure mercury lamps -low pressure sodium lamps-low pressure sodium lamps -high pressure sodium lamps-high pressure sodium lamps -inductions lamps-inductions lamps
FLUORESCENT LAMPFLUORESCENT LAMP Known as tubular fluorescent lampKnown as tubular fluorescent lamp
Produces radiation in the visibleProduces radiation in the visible
COMPACT FLUORESCENT LAMPCOMPACT FLUORESCENT LAMP
Smaller versions of long distance Smaller versions of long distance tubetube
HIGH PRESSURE MERCURY HIGH PRESSURE MERCURY LAMPSLAMPS
Consists of quartz arc tubeConsists of quartz arc tube
Used in industrial & road lightiningUsed in industrial & road lightining
LOW PRESSURE SODIAM LAMPLOW PRESSURE SODIAM LAMP
Radiation emitted from these lamp is Radiation emitted from these lamp is monochromaticmonochromatic
Used for street lighteningUsed for street lightening
HIGH PRESSURE SODIUM LAMPHIGH PRESSURE SODIUM LAMP
Emit more continuous spectrumEmit more continuous spectrum
Have better colour propertiesHave better colour properties
Used in road lightning , sports hallUsed in road lightning , sports hall
INDUCTION LAMPSINDUCTION LAMPS New typeNew type
Known as eletrodeless lampKnown as eletrodeless lamp
ADV OF DISCHARGE LAMPSADV OF DISCHARGE LAMPS Lamp life longerLamp life longer
Excellent colour rendering propertiesExcellent colour rendering properties