The formula D^2 = 4050 / i indicates the amount of illumination (i) , in foot-candles, produced by a light source relative to the distance (d) from the source. How far from the source is the illumination equal to 50 foot-candles?© BrainMass Inc. brainmass.com March 4, 2021, 6:22 pm ad1c9bdddf
Substitute i = 50 into your equation this gives D^2 = 4050/50 or ...
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