Poynting Vector
A vector representing the directional energy flux density (power per unit area) transported by an electromagnetic field.
Governing formula
S = (1 / μ₀) (E × B)
SI unit
W/m² (Watts per square meter)
In depth
The Poynting vector points in the direction of electromagnetic wave propagation. Its time-averaged magnitude represents wave intensity (I = ⟨S⟩).
Examples in the real world
Calculating directional solar radiation power reaching Earth's upper atmosphere (~1361 W/m²).