Clarification on field intensity (electromagnetism)

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Main Question or Discussion Point

Is the intensity of a general electromagnetic wave always the norm of its Poyinting vector?
Or are there other notions of intensity?
 

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  • #2
vanhees71
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Since by definition "intensity" is the energy flux per unit time that's right, but usually you have to take also the temporal average. Also see

https://de.wikipedia.org/wiki/Intensität_(Physik)

Note that the energy flux for an em. field (in vacuo) is given by the Poynting vector
$$\vec{I}=\vec{S}=\frac{1}{\mu_0} \vec{E} \times \vec{B}.$$
 
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