Light is a form of energy that moves from one body to another without the need for a physical medium in the space between the two bodies. This form is radiation that travels in the form of straight lines from the source and in all directions.
Lighting units:
1. LUMINOUS FLUX: It is the amount of light that a light source gives off in one second.
It is measured in (lumen).
1 lumen =1 Wat of light
1 Wat of light = WAT * 555 nm
555 nm: It is the relative yield of eye sensitivity.
2. LUMINOUS INTENSITY: It is the amount of light emitted within a stereoscopic angle of one degree in a given direction.
It is measured in (Candle).
3. luminance level: is a measure of the degree of concentration of light falling on a surface.
It is denoted by a symbol (E).
It is measured in (lux).
1 lux =1 lumen/m2
In English units, luminance is measured in (Foot-Candle).
Foot-Candle: fc
1 fc= 1 lm/ft2
1fc=10.76 lux.
1lux=0.093lm/ft2
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Photoflux (o).
illuminated surface (s)
E=O/S
4.LUXINANCE: The LUXINANCE of a luminous surface or a reflective surface is defined as the light intensity of the surface in a specific direction divided by its projected area.
symbolizes it (L).
It is measured in (cd/cm2).
L=I/Scos a
The real area of the luminous or reflective surface (s).
The projected or apparent area in the direction of the light intensity (Scosa).
Optical intensity (I).
In reflective surfaces, which have the characteristic of regular embossing, it gives clarity in relation:
L=E*r/
Surface reflection coefficient (r).
This means that the greater the reflection coefficient of the surface, the greater its brightness or sunrise, i.e. light surfaces appear more illuminated than dark surfaces.
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LUMEN
Regular bike light: 10 lm.
Incandescent lamp 150w: 1940 lm.
fluorescent lamp 40w: 1800 lm.
Sodium vapor lamp 140w: 13000 lm.
Mercury vapor lamp 400w: 20000 lm.
luminance level
Midday in the summer open site and clear skies 100000 lux.
Midday in winter and open site10000 lux.
Midday in the summer and under the porch 20000-5000 lux.
Midday in the summer and behind the window 1000-3000 lux.
Sunrise and sunset 500 lux.
A night when the moon is full and the sky is clear 0.25 lux.
On a work table in a well-lit living room 500 lux.
Well lit office 800 lux.
Candle
Front bicycle headlight without reflector 1cd.
Front bike headlight with reflector 250 cd.
Mirror mirror lamp 150w And on the main axis 20000 cd.
Beacon and on the main axis 2000000 cd.
cd/cm2
sun 165000 cd/m2.
moon0.25 cd/m2 .
Incandescent lamp filament 700 cd/m2 .
Incandescent lamp 20 cd/m2 .
Fluorescent lamp in the transverse direction 8000 cd/m2 .
Fluorescent lamp in the longitudinal direction 5000 cd/m2 .
White papers (reflection factor 80%) and lighting adjustment 400 lux 100 cd/m2 .
gray paper (reflection factor 40%) and lighting adjustment 400 lux 50 cd/m2 .
black paper (reflection factor 4%) and lighting adjustment 400 lux 5 cd/m2.