Light intensity {illuminance}| is light flux (in lumens) per area. Light intensity depends on amplitude squared, photon number, and frequency squared.
Light intensity {Poynting vector} has maximum of half times light speed times permittivity e times electric field E squared: 0.5 * c * e * E^2. Poynting vector equals half times electric field E times magnetic field H: 0.5 * E * H.
At high intensity, wave electric field can affect molecule electric fields {Kerr effect} {optical Kerr effect}.
Radiation has pressure {radiation pressure} {pressure, radiation} from photon flow. Pressure P equals energy U divided by three times volume V: P = U / (3*V).
Light meters {photometer}| can measure light intensity.
5-Physics-Wave-Electromagnetic
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Date Modified: 2022.0225