19. At a distance r = 10 m from the point of monochromatic (λ = 0,6 m) is an isotropic source area (S = 10 mm 2) is perpendicular to the incident beam. Determine the number n of photons every second falling on the ground. P Power light is 800 watts.

Detailed solution. Decorated in Microsoft Word 2003. (Target decided to use formula editor)