3 Transfer and Conversion of Field Power

3.1 Poynting’s Theorem: Poynting Vector*

The basis for investigating energy motion in electromagnetic fields is Poynting’s theorem [3.3] and the Poynting vector (Turowski [1.15], [3.4]). Poynting’s theorem says that:

The electromagnetic power Ps flowing into (or flowing out of) a closed volume, across an enclosing surface A, equals to the surface integral of the normal component of the Poynting vector Sn over the entire enclosed surface A:

Ps=ASdA=ASn dA(3.1)



is the Poynting vector, which determines the power and direction of the electromagnetic power flux passing through a surface unit perpendicular to the energy flow direction. Of course,


Poynting’s theorem can ...

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