In Physics 7C we learn that power is the integral of light intensity with respect to area. If we assume that the power of light emanating from the source is constant and there is uniform intensity in all directions, we can calculate intensity as I = P/(4pi r^2), which tells us that Intensity is inversely proportional to r^2.

In Physics 7C we learn that power is the integral of light intensity with respect to area. If we assume that the power of light emanating from the source is constant and there is uniform intensity in all directions, we can calculate intensity as I = P/(4pi r^2), which tells us that Intensity is inversely proportional to r^2.