Poynting Vector

In physics, the Poynting vector represents the directional energy flux density (the rate of energy transfer per unit area, in watts per square metre (W·m−2)) of an electromagnetic field. It is named after its inventor John Henry Poynting. Oliver Heaviside and Nikolay Umov independently co-invented the Poynting vector.

Read more about Poynting Vector:  Definition, Formulation in Terms of Microscopic Fields, Time-averaged Poynting Vector