Задача id16590

On three poles located in a straight line at a distance l = 20 m from one another, electric lamps are suspended at a height h = 4 m above ground level, consuming power N0 = 1 kW each. Find the illumination at a point on the ground under the first pillar if the luminous flux of each lamp is Ф = 15·103 lm. What percentage of the illumination of the earth from the lamp on the first pillar is the illumination from the lamp on the second and third pillars?

Detailed solution. Format gif