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Luminous efficacy can be normalized by the maximum possible luminous efficacy to a dimensionless quantity called luminous efficiency.The distinction between efficacy and efficiency is not always carefully maintained in published sources, so it is not uncommon to see "efficiencies" expressed in lumens per watt, or "efficacies" expressed as a percentage.
In painting, local color is the color of an object when seen under flat white light with no adjustment for form shadow or colors of light or secondary light sources. An example would be the assumption that an apple is "red" when it is actually dependent on the color of the light hitting it, color of objects around it, glossiness, and variations within the colors on the surface of the apple itself.
Effective mode volume is proportional to the breadth of the relative distribution of power amongst the modes in a multimode fiber. It is not truly a spatial volume but rather an "optical volume" equal to the product of area and solid angle. The power divided by the effective mode volume is proportional to the radiance of the light emitted by ...
Rating and marketing emphasis is shifting away from wattage and towards lumen output, to give the purchaser a directly applicable basis upon which to select a lamp. Lamp types include: Ballast : A ballast is an auxiliary piece of equipment designed to start and properly control the flow of power to discharge light sources such as fluorescent ...
A 230-volt LED filament lamp, with an E27 base. The filaments are visible as the eight yellow vertical lines. An assortment of LED lamps commercially available in 2010: floodlight fixtures (left), reading light (center), household lamps (center right and bottom), and low-power accent light (right) applications An 80W Chips on board (COB) LED module from an industrial light luminaire, thermally ...
Lumen maintenance is the most useful gauge to determine the lifetime or useful light output rating of an LED light source. Unlike traditional light sources such as incandescent lamps, LEDs rarely fail outright and instead continue to emit light, albeit at slowly diminishing rate over time. [ 1 ]
The whole detailed discussion about lumen output of 120V vs 230V lamps is off-topic for this page defining and discussing lumen. Take it to a luminous efficacy page, if there is one. Here just give an example like a "typical" candle at about 10 lm, a 100W bulb at about 1500 lm, a streetlight at 20,000-50,000 lm.
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.