Poynting vector

Measure of directional electromagnetic energy flux

In physics, the Poynting vector (or Umov–Poynting vector) represents the directional energy flux (the energy transfer per unit area, per unit time) or power flow of an electromagnetic field. The SI unit of the Poynting vector is the watt per square metre (W/m²); kg/s3 in SI base units. It is named after its discoverer John Henry Poynting who first derived it in 1884.

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