The Poynting Vector, Energy Density, and Intensity of Electromagnetic Radiation

I derive and define the Poynting vector, and show mathematically its relationship to the energy density and the intensity. A simple example problem is also shown.

[nikannow]

That was great! One question, is heat in the form of thermal radiation a portion of the total power calculated here? Is there a book that makes the link between the equation you derived here and the one for thermal radiation? I've only seen them separately in textbooks.