ILLUMINATION

OBJ

Luminous Flux (Φ)

• All the radiated power emitted by a light source and perceived by the eye

• light output of a light source

Lumen (lm)

unit of measurement of the light output of a lamp

Luminous Intensity (I)

• a light source emits its luminous flux (Φ) in different directions and at different intensities. is a measure of how much flux is emitted within a small conical angle in the direction of the surface

candela (cd)

SI unit for luminous intensity

Light Intensity

is the measure of light output in a specified direction or particular direction

Illuminance (E)

is a measure of the amount of light falling on a surface. The distance of the light source from the area being illuminated influences it.

Lux (lx)

The International System of Units (SI) unit of illuminance

Luminance (L)

is the brightness of an illuminated or luminous surface as perceived by the human eye.

Luminous Efficacy (η)

indicates the efficiency with which the electrical power consumed is converted into light

Luminaire Efficiency

(also known as the light output ratio) is an important criterion in gauging the energy efficiency of a luminaire.

Incandescent lamps

produce light by the passage of an electric current through a filament, which heats it to incandescence

Electric discharge lamps

produce light by the passage of an electric current through a vapor or gas, initiating the discharge to fluoresce.

Light

is a form of radiant energy from natural sources (e.g. the sun and stars), and artificial sources (e.g. a candle and electric lamps).

Lighting

Is the application of light to illuminate objects, surfaces, scenes, pictures and people.

Illumination

Average illumination of a surface is luminous flux per unit area

Incandescent Lamps

produce light by the passage of an electric current through a filament, which heats it to incandescence (e.g. general service, reflectorized, and tungsten-halogen).

Electric Discharge lamps

produce light by the passage of an electric current through a vapor or gas, initiating the discharge to fluoresce.

Illumination meter

An instrument used to measure the intensity of a light source

Coefficient of utilization

The ratio of lumens reaching the work plane divided by the total lumens generated by the light is

Candela

Unit of luminous intensity

Lux

Unit of illuminance

Glare and shadows

The direct lighting scheme is most efficient but is liable to cause______

Utilization Factor

Total flux required in any lihting scheme depends inversely on______

Reading

Flood is NOT used for ________ purposes

Incandescent

Has minimum initial cost of installation but maximum running cost

4000

The average working life of a fluorescent lamp is about _____ hours

70

The luminous efficiency of a sodium vapor lamp is about____ lumden

Efficacy

A measure of lumen output per watt input produced by the light source

Cinema Projector

Carbon arc lamps are commonly ussd in____

Proofreading

Need hughest level of illumination

Lux

Illumination of one lumen pe sq. Meter is called_____

Trotter Illumination Photometer

Depends on its operation on Lamberts cosine law

Ambient Temperature

The level of illumination on surface least relies upon_______

6000 K

The color temperature of day light is around_____

Osmium

Filament material that has lowest melting point

Tungsten

A material used as filament in the incandescent lamps?

Luminous efficiency

Lumen

3400 deg C

Melting point of tungsten

Unity

Power factor of filament lamps