Intensity

#Physics
Average power per unit area

$\displaystyle I=\frac{\bar{n}_{t}h\nu}{At}$

• $\displaystyle \bar{n}_{t}$ is the average number of photons

$\displaystyle I\equiv {\left\langle{S}\right\rangle}=\frac{1}{2}c{\varepsilon}{0}E{0}^{2}$

• $\displaystyle S$ is the Poynting vector
• $\displaystyle E_{0}$ is the max amplitude of the electric field of the electromagnetic wave