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  2. Fluorescent-lamp formats - Wikipedia

    en.wikipedia.org/wiki/Fluorescent-lamp_formats

    High-lumen retrofit lamps for 40W T12 lamps in North America. Popular tube diameter in Japan; Circular 32W and 40W T10 lamps (Older versions of the 32W and 40W T9 lamps) T12 T38 1 + 1 ⁄ 2: 38.1 G13 bi-pin; Fa8 single-pin; R17d recessed double contact; One of the first diameters of fluorescent lamps, with the 15W T12 and 20W T12 having been ...

  3. Lumen (unit) - Wikipedia

    en.wikipedia.org/wiki/Lumen_(unit)

    The lumen (symbol: lm) is the unit of luminous flux, a measure of the perceived power of visible light emitted by a source, in the International System of Units (SI). Luminous flux differs from power ( radiant flux ), which encompasses all electromagnetic waves emitted, including non-visible ones such as thermal radiation ( infrared ).

  4. Orders of magnitude (illuminance) - Wikipedia

    en.wikipedia.org/wiki/Orders_of_magnitude...

    To help compare different orders of magnitude, the following list describes various source in lux, which is a lumen per square metre. Factor Multiple Value

  5. Color temperature - Wikipedia

    en.wikipedia.org/wiki/Color_temperature

    Color temperatures over 5000 K are called "cool colors" (bluish), while lower color temperatures (2700–3000 K) are called "warm colors" (yellowish). "Warm" in this context is with respect to a traditional categorization of colors, not a reference to black body temperature.

  6. Lux - Wikipedia

    en.wikipedia.org/wiki/Lux

    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.

  7. Luminous efficacy - Wikipedia

    en.wikipedia.org/wiki/Luminous_efficacy

    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.

  8. Candela per square metre - Wikipedia

    en.wikipedia.org/wiki/Candela_per_square_metre

    lux (= lumen per square metre) lx (= lm/m 2) L −2 ⋅J: Luminous flux incident on a surface Luminous exitance, luminous emittance M v: lumen per square metre lm/m 2: L −2 ⋅J: Luminous flux emitted from a surface Luminous exposure: H v: lux second: lx⋅s L −2 ⋅T⋅J: Time-integrated illuminance Luminous energy density ω v: lumen ...

  9. Guide number - Wikipedia

    en.wikipedia.org/wiki/Guide_number

    Unit: Lumen⋅second Definition: In the context of flash devices, is the measure of the total energy, or quantity, of eye-adjusted visible light emitted over a period of time. In common vernacular, it is the total amount of light released over the course of a flash. Illuminance Symbol: E v Unit: Lux (lumens per square meter)