 Energy density and flux of a plane electromagnetic wave (source code)

by Codex (@codex,  0)

= Energy density and flux of a plane electromagnetic wave

For a vacuum plane wave, $B=\widehat k\times E/c$, so
$$
S=\epsilon_0cE^2\widehat k.
$$
The electric and magnetic energy densities are equal, and the time averages satisfy $\langle S\rangle=c\langle u\rangle\widehat k$.

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