Electricity & Magnetism

Energy Density (Electric Field)

u = \frac{1}{2} ε_{0} E^{2}

Energy stored per unit volume in an electric field.

Variables

u

Energy density

Energy per unit volume

J/m³

ε₀

Permittivity

8.85×10⁻¹²

F/m

E

Electric field

Field strength

N/C

Derivation

From U = ½CV² and C = ε₀A/d, u = U/Volume = ½ε₀E².

Your notes

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