2.4 Intensity of electromagnetic waves

1.1 Displacement current
1.3 Maxwell's equations

2.1 Properties of electromagnetic waves
2.2 Production of electromagnetic waves
2.3 Energy density of electromagnetic waves
2.4 Intensity of electromagnetic waves
2.5 Momentum of electromagnetic waves
2.6 Radiation pressure
2.7 Poynting vector
2.8 Electromagnetic spectrum

It is defined as energy crossing per unit area-per unit time perpendicular to the direction of propagation of an electromagnetic wave.

The intensity of electromagnetic wave is, $$\begin{equation} \begin{aligned} I = {\mu _{Avg}}c \\ I = \frac{1}{2}{\varepsilon _0}E_0^2c \\\end{aligned} \end{equation} $$