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The inverse-square law, greatly simplified, states that the intensity
of light (or any other radiant energy), if the light strikes the
target at a right angle, varies inversely according to the square of
the distance from the source.
In other, simpler, words....
- In the example above, the light strikes Fred Flintstone at a
25' throw and its intensity is 100 footcandles.
- The throw to Duckman is 2 times as
far. The square of 2 is 4 and the
inverse of 4 is ¼.
- Therefore, the intensity of light on Duckman is
25 footcandles, because
25 is ¼ of the 100 footcandles striking Fred Flintstone.
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