Figure 7. There are N current elements in the region, some of which are radiation sources in red, some sinks in blue, and Γ is the boundary surface of the region

From

The Theory of Mutual Energy Flow Proves that Macroscopic Electromagnetic Waves are Composed of Photons

Shuang-ren Zhao

International Journal of Physics. 2022, 10(4), 218-235 doi:10.12691/ijp-10-4-4