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Radiant flux per unit frequency or wavelength. The latter is commonly measured in W⋅nm −1. Φ e,λ [nb 4] watt per metre W/m M⋅L⋅T −3: Radiant intensity: I e,Ω [nb 5] watt per steradian: W/sr: M⋅L 2 ⋅T −3: Radiant flux emitted, reflected, transmitted or received, per unit solid angle. This is a directional quantity. Spectral ...
Radiant energy emitted, reflected, transmitted or received, per unit time. This is sometimes also called "radiant power", and called luminosity in Astronomy. Spectral flux: Φ e,ν [nb 3] watt per hertz: W/Hz: M⋅L 2 ⋅T −2: Radiant flux per unit frequency or wavelength. The latter is commonly measured in W⋅nm −1. Φ e,λ [nb 4] watt ...
The relative spectral flux density is also useful if we wish to compare a source's flux density at one wavelength with the same source's flux density at another wavelength; for example, if we wish to demonstrate how the Sun's spectrum peaks in the visible part of the EM spectrum, a graph of the Sun's relative spectral flux density will suffice.
A flow chart describing the relationship of various physical quantities, including radiant flux and exitance. In radiometry, radiant flux or radiant power is the radiant energy emitted, reflected, transmitted, or received per unit time, and spectral flux or spectral power is the radiant flux per unit frequency or wavelength, depending on whether the spectrum is taken as a function of frequency ...
To calculate the flux density in janskys, the total power detected (in watts) is divided by the receiver collecting area (in square meters), and then divided by the detector bandwidth (in hertz). The flux density of astronomical sources is many orders of magnitude below 1 W·m −2 ·Hz −1 , so the result is multiplied by 10 26 to get a more ...
Irradiance of a surface per unit frequency or wavelength. This is sometimes also confusingly called "spectral intensity". Non-SI units of spectral flux density include jansky (1 Jy = 10 −26 W⋅m −2 ⋅Hz −1) and solar flux unit (1 sfu = 10 −22 W⋅m −2 ⋅Hz −1 = 10 4 Jy). E e,λ [nb 4] watt per square metre, per metre W/m 3: M⋅L ...
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).
Radiant flux: Φ e [nb 2] watt: W = J/s M⋅L 2 ⋅T −3: Radiant energy emitted, reflected, transmitted or received, per unit time. This is sometimes also called "radiant power", and called luminosity in Astronomy. Spectral flux: Φ e,ν [nb 3] watt per hertz: W/Hz: M⋅L 2 ⋅T −2: Radiant flux per unit frequency or wavelength. The latter ...