The Poynting vector, named after John Henry Poynting, is a mathematical quantity used in physics to represent the directional energy flux (or power per unit area) of an electromagnetic field. It describes the flow of electromagnetic energy in a particular direction through space.
The formula for the Poynting vector () is given by:
Where:
- is the Poynting vector (W/m²),
- is the electric field vector(V/m),
- is the magnetic field vector (A/m).
The SI unit of the Poynting vector is watts per square meter (W/m²), as it represents the power (watts) per unit area (square meter) carried by the electromagnetic field.