I don’t even know where to start for this problem:
Two lamps are of intensities 40 and 5 candle-power respectively, and are 6 m apart. If the intensity of Illumination, I, at any point is directly proportional to the power of the source and inversely proportional to the square of the distance from the source, find the darkest point on the line joining the two lamps.

Popularity: 1% [?]