Energy density in electromagnetic fields (u = ½ε₀E² + B²/(2μ₀); traveling EM wave in vacuum: u =)
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u = ½ε₀E² + B²/(2μ₀); traveling EM wave in vacuum: u = ε₀E² = B²/μ₀
What each symbol means
| Symbol | What it stands for |
|---|---|
| B | Magnetic field magnitude (T) |
| E | Electric field magnitude (V/m) |
| u | Energy density (J/m³) |
When to use this
Superposition of general fields uses sum of electric and magnetic parts; for plane EM wave in vacuum instantaneous electric and magnetic energy densities are equal.