The inverse-square law correlates Illumination of the surface (E), luminous intensity (I) and the distance between the source and the surface to be illuminated (r) by the formula:
1
\(E = \frac{{{I^2}}}{r}\)
2
\(E = \frac{I}{r}\)
3
\(E = \frac{I}{{{r^2}}}\)
4
\(E = {I^2}r\)
5
\(E = \frac{I}{{{r^3}}}\)