Clarification on field intensity (electromagnetism)

In summary, field intensity or electric field strength is a measure of the strength of an electric field at a specific point in space. It is calculated by dividing the force acting on a charge by the magnitude of the charge and can also be expressed using the equation E = kQ/r^2. The SI unit for field intensity is volts per meter (V/m), but it can also be measured in newtons per coulomb (N/C) or teslas (T). The stronger the field intensity, the greater the force exerted on objects in its presence, potentially causing them to move or change shape.
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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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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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