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A fluorescent lamp, or fluorescent tube, is a low-pressure mercury-vapor gas-discharge lamp that uses fluorescence to produce visible light. An electric current in the gas excites mercury vapor, to produce ultraviolet and make a phosphor coating in the lamp glow.
Typical photographic scene in full sunlight [7] [9] 7 kcd/m 2: Average clear sky [4] [5] [6] [12] 10 kcd/m 2: White illuminated cloud [6] 12 kcd/m 2: Fluorescent lamp [5] [6] 10 5: 75 kcd/m 2: Low pressure sodium-vapor lamp [6] 130 kcd/m 2: Frosted incandescent light bulb [5] [6] [12] 10 6: Mcd/m 2: 600 kcd/m 2: Solar disk at horizon [5] 10 7: ...
Mathematically, for the spectral power distribution of a radiant exitance or irradiance one may write: =where M(λ) is the spectral irradiance (or exitance) of the light (SI units: W/m 2 = kg·m −1 ·s −3); Φ is the radiant flux of the source (SI unit: watt, W); A is the area over which the radiant flux is integrated (SI unit: square meter, m 2); and λ is the wavelength (SI unit: meter, m).
Full-spectrum light is light that covers the electromagnetic spectrum from infrared to near-ultraviolet, or all wavelengths that are useful to plant or animal life; in particular, sunlight is considered full spectrum, even though the solar spectral distribution reaching Earth changes with time of day, latitude, and atmospheric conditions.
Sunlight is a portion of the electromagnetic radiation given off by the Sun, in particular infrared, visible, and ultraviolet light. On Earth , sunlight is scattered and filtered through Earth's atmosphere as daylight when the Sun is above the horizon .
The theory of solar cells explains the process by which light energy in photons is converted into electric current when the photons strike a suitable semiconductor device. The theoretical studies are of practical use because they predict the fundamental limits of a solar cell , and give guidance on the phenomena that contribute to losses and ...
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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.