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Luminous efficacy is a measure of how well a light source produces visible light. ... Sources that depend on thermal emission from a solid filament, ...
Luminous efficacy is measured in lumens per watt (lm/W). The luminous efficiency of a source is defined as the ratio of its luminous efficacy to the maximum possible luminous efficacy, which is 683 lm/W. [80] [81] An ideal white light source could produce about 250 lumens per watt, corresponding to a luminous efficiency of 37%. [82]
The luminous efficacy of lamps is the number of lumens emitted for each watt of electric power used. The luminous efficacy of a typical CFL is 50–70 lumens per watt (lm/W) and that of a typical incandescent lamp is 10–17 lm/W. [38]
In heat lamps, such as those used for incubators (or the Easy-Bake Oven), heat from the filament is the goal. But anytime a bulb is used for light and not heat, these bulbs are a poor choice.
This is a list of sources of light, the visible part of the electromagnetic spectrum.Light sources produce photons from another energy source, such as heat, chemical reactions, or conversion of mass or a different frequency of electromagnetic energy, and include light bulbs and stars like the Sun. Reflectors (such as the moon, cat's eyes, and mirrors) do not actually produce the light that ...
A filament may also break, disabling the lamp. This tube failed after it had been turned on many times. Too much of the thermionic emission mix had sputtered off the cathodes, sticking to and blackening the glass. The filament of a low-pressure mercury gas-discharge lamp, with white thermionic emission coating acting as hot cathode.
Photoluminescence (abbreviated as PL) is light emission from any form of matter after the absorption of photons (electromagnetic radiation). [1] It is one of many forms of luminescence (light emission) and is initiated by photoexcitation (i.e. photons that excite electrons to a higher energy level in an atom), hence the prefix photo- . [ 2 ]
This allows the filament to operate at a higher temperature than a standard incandescent lamp of similar power and operating life; this also produces light with higher luminous efficacy and color temperature. The small size of halogen lamps permits their use in compact optical systems for projectors and illumination. The small glass envelope ...