# Poynting Vector

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## Poynting vector

[′pȯint·iŋ ‚vek·tər]## Poynting Vector

the vector of the flux density of electromagnetic energy; named after the English physicist J. H. Poynting (1852–1914).

The magnitude of the Poynting vector is equal to the energy transferred per unit time through a unit of surface perpendicular to the direction of propagation of the electromagnetic energy, that is, to the direction of the Poynting vector. In the absolute (Gaussian) system of units, Π = (e/π)**[EH]**, where **[EH]** is the vector product of the intensities of the electric flux **E** and magnetic field **H** and *c* is the speed of light in a vacuum; in the International System, Π = **[EH]**. The flow of the Poynting vector through a closed surface bounding a system of charged particles gives the value of the energy lost by the system per unit time as a result of the emission of electromagnetic waves. The momentum density of an electromagnetic field g is expressed in terms of the Poynting vector:

G. IA. MIAKISHEV