>> Your prof was correct. Semantic domains, etymology, and all those >> little tidbits of trivia are interesting- but not useful in the final >> analysis because words gain meaning only from context. >[....] >> To isolate a word and assign it meaning is futile. >[....] > >There is more context to the text than the words proximate to >the text.
When looking at brightness specifications of LEDs, the most common specs available are luminous intensity (usually measured in units of candelas or millicandelas) and viewing angle (measured in degrees). The brightness of 1 candela is roughly around the same brightness as a common candle. A millicandela, or mcd, is 1000 times less bright than a candela, hence the prefix milli-. 1000 millicandelas = 1 candela. Since light is not always evenly dispersed, the viewing angle of a light source is very important.
Illuminance = Light Falling on a Surface. The amount of light falling on a surface is illuminance, and is measured in lux (metric unit = lumen/m 2) or foot-candles (English unit = lumen/ft 2).1 footcandle equals 10.8 lux.he brightness of light can mean different things: for example, the amount of light coming from a light source is luminous flux (lumens), the amount of light falling on a surface is illuminance (lux), and the amount of light reflected off a surface is luminance (cd/m2).