Difference between revisions of "Power density"

From Glossary of Meteorology
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<div class="definition"><div class="short_definition">In an [[electromagnetic wave]], the rate of [[power]] flow in a specific direction at a  particular point in a transmission medium, expressed as [[energy]] per unit time (power, or [[radiant  flux]]) per unit cross-sectional area normal to the direction of propagation.</div><br/> <div class="paragraph">The power density generally diminishes with increasing distance from the source as a result of  [[absorption]], [[reflection]], [[scattering]], and possibly other effects, as well as geometric spreading of  the [[beam]]. For surfaces or objects that intercept the [[radiation]] at a sufficiently long distance from  the source, the propagating energy may be regarded as plane-wave or parallel-beam radiation. Then  the power density is the same as the [[irradiance]] at a surface normal to the beam.</div><br/> </div>
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<div class="definition"><div class="short_definition">In an [[electromagnetic wave]], the rate of [[power]] flow in a specific direction at a  particular point in a transmission medium, expressed as [[energy]] per unit time (power, or [[radiant flux|radiant  flux]]) per unit cross-sectional area normal to the direction of propagation.</div><br/> <div class="paragraph">The power density generally diminishes with increasing distance from the source as a result of  [[absorption]], [[reflection]], [[scattering]], and possibly other effects, as well as geometric spreading of  the [[beam]]. For surfaces or objects that intercept the [[radiation]] at a sufficiently long distance from  the source, the propagating energy may be regarded as plane-wave or parallel-beam radiation. Then  the power density is the same as the [[irradiance]] at a surface normal to the beam.</div><br/> </div>
 
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Latest revision as of 17:39, 25 April 2012



power density

In an electromagnetic wave, the rate of power flow in a specific direction at a particular point in a transmission medium, expressed as energy per unit time (power, or radiant flux) per unit cross-sectional area normal to the direction of propagation.

The power density generally diminishes with increasing distance from the source as a result of absorption, reflection, scattering, and possibly other effects, as well as geometric spreading of the beam. For surfaces or objects that intercept the radiation at a sufficiently long distance from the source, the propagating energy may be regarded as plane-wave or parallel-beam radiation. Then the power density is the same as the irradiance at a surface normal to the beam.