Solution to task 575 from Chertov´s for extramural stud

Solution to task 575 from Chertov´s for extramural stud

575. At a distance r = 5 m from a point monochromatic (λ = 0.5 µm) isotropic source, there is an area (S = 8 mm2) perpendicular to the incident beams. Determine the number N of photons incident on the site every second. Radiation power P = 100 W.