Poynting vector (energy flux density) (S = (E×B)/μ₀; |S| = EB/μ₀)
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S = (E×B)/μ₀; |S| = EB/μ₀
What each symbol means
| Symbol | What it stands for |
|---|---|
| B | Magnetic field (T) |
| E | Electric field (V/m) |
| S | Poynting vector (W/m²), power per unit area crossing surface |
| μ₀ | Permeability of free space |
When to use this
Vacuum (or use μ for medium). Direction of S is direction of energy flow (propagation for plane wave).