Lux
Historical document, translated for reference. It reflects medical knowledge of the 1920s–30s and is not medical advice.
Summary
The lux is a practical unit of illuminance defined as the illumination of a surface of one square meter by a uniformly distributed luminous flux of one lumen. It is equivalent to 0.0001 phot and 0.093 foot-candle.
Encyclopedia entry (1928–1936)
Lux, a practical unit of illuminance. The lux is defined as the illumination of a surface of one m2, created by a uniformly distributed luminous flux of one lumen, or as the illumination on the inner surface of a sphere with a radius of one m from a point light source with a luminous intensity of one international candle, radiating uniformly in all directions and located at the center of this sphere. - The lux constitutes 0.0001 phot, currently accepted as the international unit of illuminance, and 0.093 foot-candle, used as a unit of illuminance in America. It is necessary to distinguish the lux from the international lux of Hefner, often also called the candle-meter, which is still in use in Germany and constitutes 0.885 of the international lux. The Hefner lux is based on the old unit of luminous intensity - the Hefner candle.
Related articles
Mentioned in
Cite this page
“Lux.” Soviet Medical Encyclopedia. English translation of Bolshaya Meditsinskaya Entsiklopediya, 1st ed. (Moscow, 1928–1936), ed. N. A. Semashko. https://sovietmedicalencyclopedia.pages.dev/article/lux/