Lambert- A
cgs unit of luminance (or photometric brightness) equal to one lumen, or 1/ pie
candela per square centimeter; this luminance is produce by a blackbody source
of luminous intensity 1 candela at a distance of 1 centimeter (the corresponding
SI (or mks) unit is the apostilb, a unit 104 smaller produced by 1 candela at a
distance of 1 m; the sun's disk at zenith at sea level under clear skies has a
luminance of about 470,000 lambert, while that of a 60-watt, inside-frosted,
tungsten-filament light bulb is about 38 lambert).
Liter- The
basic metric unit of volume; 3,785 liters equals 1 U.S. gallon (1 liter of water
weights 1000 grams).
Lumens- A unit
of photometric power; the lumen is equal to the amount of photometric power
radiated into a unit solid angle (steradian) from a small source having a
luminous intensity of one candela (Tungsten-filament light bulbs produces
approximately 15 lumens per watt).
Lux- A
photometric unit of illuminance or illumination equal to one lumen per square
meter (a level of illumination between 200 and 1000 lux is generally considered
to be adequate for homes and offices).
