Final answer:
The inverse square law states that the intensity of radiation at a given area is inversely related to the square of the distance from the source, with the equation I = P / (4 π r^2).
Step-by-step explanation:
The inverse square law refers to the principle that the intensity of radiation at a given area is inversely related to the square of the distance between the point of origin and the area of interest. The equation representing this law is I = P / (4 π r^2), where I represents the intensity, P is the total power radiated by the source, and r is the distance from the source. This law applies to various forms of radiative phenomena such as light and gravity, where the decrease in intensity or force with distance is proportional to 1/r^2.