Poynting vector

The Poynting vector is a vector quantity representing a flow of electromagnetic energy at a point, defined by

⃗ 𝐒 = 1 𝜇 0 ⃗ 𝐄 \times ⃗ 𝐁

To see how this represents energy flow, see Poynting’s theorem. The Poynting vector is related to Electromagnetic momentum density by

⃗ 𝐠 = 𝜖 0 𝜇 0 ⃗ 𝐒