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However, in the lighting industry it is often associated with the lighting power allowance (LPA) permitted by the building energy code in question. The Oregon Department of Energy defines lighting power density as "The maximum allowable lighting density permitted by the code. It is expressed in watts per square foot for a given occupancy/space ...
Radiant intensity, a radiometric quantity measured in watts per steradian (W/sr) Luminous intensity, a photometric quantity measured in lumens per steradian (lm/sr), or candela (cd) Irradiance, a radiometric quantity, measured in watts per square meter (W/m 2) Intensity (physics), the name for irradiance used in other branches of physics (W/m 2)
As the source emits electromagnetic radiation of a given wavelength, the far-field electric component of the wave E, the far-field magnetic component H, and power density are related by the equations: E = H × 377 and Pd = E × H. Pd = H 2 × 377 and Pd = E 2 ÷ 377 where Pd is the power density in watts per square meter (one W/m 2 is equal to ...
Electromagnetic radiation power per unit surface area W/m 2: M T −3: intensive Intensity: I: Power per unit cross sectional area W/m 2: M T −3: intensive Linear density: ρ l: Mass per unit length kg⋅m −1: L −1 M: Luminous flux (or luminous power) F: Perceived power of a light source lumen (lm = cd⋅sr) J: Mach number (or mach) M
Luminous energy density ω v: lumen second per cubic metre lm⋅s/m 3: L −3 ⋅T⋅J: Luminous efficacy (of radiation) K: lumen per watt: lm/W: M −1 ⋅L −2 ⋅T 3 ⋅J: Ratio of luminous flux to radiant flux: Luminous efficacy (of a source) η [nb 3] lumen per watt: lm/W: M −1 ⋅L −2 ⋅T 3 ⋅J: Ratio of luminous flux to power ...
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).
In physics and many other areas of science and engineering the intensity or flux of radiant energy is the power transferred per unit area, where the area is measured on the plane perpendicular to the direction of propagation of the energy. [a] In the SI system, it has units watts per square metre (W/m 2), or kg⋅s −3 in base units.
Table of comparative luminous flux of several light sources [7] [8] [9] Source Luminous flux (lumens) 37 mW "Superbright" white LED: 0.20 15 mW green laser (532 nm wavelength) 8.4 1 W high-output white LED: 25–120 Kerosene lantern: 100 40 W incandescent lamp at 230 volts: 325 7 W high-output white LED: 450 6 W COB filament LED lamp: 600 18 W ...