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see photometryphotometry
, branch of physics dealing with the measurement of the intensity of a source of light, such as an electric lamp, and with the intensity of light such a source may cast on a surface area.
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A unit of measurement for the average light on a surface; 1 foot-candle equals 1 lumen per square foot.
Illustrated Dictionary of Architecture Copyright © 2012, 2002, 1998 by The McGraw-Hill Companies, Inc. All rights reserved
References in periodicals archive ?
A fluorescent light, for example, casts as much as 900 foot-candles of light, but that's only within 6 inches of the light bulb.
Table I Comparison of measurements of reflective illumination of most common illuminated stand magnifiers (measurements are in foot-candles).
In Facility 2, however, residents were eating at tables with illumination of less than five foot-candles. "This facility had a limited budget for modification, so we replaced the existing fixtures with four-bulb fluorescent standard ceiling fixtures for $50 a piece that we purchased from a home improvement store," she explained.
Entrances should attain an average of 10 foot-candles of illumination, or twice the level of the immediate surroundings, whichever is greater.
We recently conducted a research project in which the dining room provided only five foot-candles of light at the table, which is well below the 50 foot-candle recommendation.
At the meeting George Brainard (Thomas Jefferson University) demonstrated how our body stops producing melatonin --an important hormone that affects sleep, aging, and reproduction--when exposed to even a tenth of a foot-candle of certain wavelengths of light.
It emits 13,00 foot-candles, producing a color-corrected, white light for truer representation of tissue color.
Vertical foot-candles are the measurement of light on the vertical plane with the meter held horizontally.
According to IESNA (1993), reading by all age groups requires light levels between 20 and 50 foot-candles (215-538 lux).
There were four house lights, which could be illuminated in combination to produce a low level (approximately 1.5 foot-candles), a medium level (approximately 17.5 foot-candles), and a high level (approximately 41 foot-candles) of illumination.
Generally, ambient illuminance levels should be lower than horizontal illuminance levels (foot-candles on the desktop) required for lighting individual tasks.