Energy flux

Energy flux is the rate of transfer of energy through a surface. The quantity is defined in two different ways, depending on the context:

  1. Total rate of energy transfer;[1] SI units: W = J⋅s−1.
  2. Specific rate of energy transfer (total normalized per unit area); [2] SI units: W⋅m−2 = J⋅m−2⋅s−1:
    • This is a vector quantity, its components being determined in terms of the normal (perpendicular) direction to the surface of measurement.
    • This is sometimes called energy flux density, to distinguish it from the second definition.
    • Radiative flux, heat flux, and sound energy flux are specific cases of this meaning.

See alsoEdit


  1. ^ "Solar Physics Glossary". Nasa. Retrieved 2008-12-24.
  2. ^ "Energy flux". Retrieved 2008-12-24.