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Factor ()Multiple Value Item 0 0 lux 0 lux Absolute darkness 10 −4: 100 microlux 100 microlux: Starlight overcast moonless night sky [1]: 140 microlux: Venus at brightest [1]: 200 microlux
Typical diameters are T12 or T38 (1 + 1 ⁄ 2 in or 38 mm) for larger, often less efficient lamps, T8 or T26 (1 in or 25 mm) for smaller and often energy-saving lamps, and T5 or T16 (5 ⁄ 8 in or 16 mm) for very small lamps, which may even operate from a battery-powered device.
Lamps used for lighting are commonly labelled with their light output in lumens; in many jurisdictions, this is required by law. A 23 W spiral compact fluorescent lamp emits about 1,400–1,600 lm. [4] [5] Many compact fluorescent lamps and other alternative light sources are labelled as being equivalent to an incandescent bulb with a specific ...
Illuminance diagram with units and terminology. In photometry, illuminance is the total luminous flux incident on a surface, per unit area. [1] It is a measure of how much the incident light illuminates the surface, wavelength-weighted by the luminosity function to correlate with human brightness perception. [2]
A foot-candle (sometimes foot candle; abbreviated fc, lm/ft 2, or sometimes ft-c) is a non-SI unit of illuminance or light intensity. The foot-candle is defined as one lumen per square foot. This unit is commonly used in lighting layouts in parts of the world where United States customary units are used, mainly the United States. [1]
In lighting design, the lumen method, (also called zonal cavity method), is a simplified method to calculate the light level in a room. The method is a series of calculations that uses horizontal illuminance criteria to establish a uniform luminaire layout in a space.
Fluorescent lighting systems spread rapidly during World War II as wartime manufacturing intensified lighting demand. By 1951 more light was produced in the United States by fluorescent lamps than by incandescent lamps. [24] In the first years zinc orthosilicate with varying content of beryllium was used as greenish phosphor. Small additions of ...
The lux (symbol: lx) is the unit of illuminance, or luminous flux per unit area, in the International System of Units (SI). [1] [2] It is equal to one lumen per square metre.In photometry, this is used as a measure of the irradiance, as perceived by the spectrally unequally responding human eye, of light that hits or passes through a surface.