What Is the Inverse Square Law and How Is It Used When Taking Photos?

The inverse square law is an equation that relates the intensity of a light source to the illumination it produces at a given distance. Light diminishes over distance in accordance with the Inverse square law, which states that doubling the light-to-subject distance reduces the light falling on the subject to one-quarter. The inverse square law can be used to calculate the light output required from a light source when setting up a photographic scene using artificial lighting, the invention of light meters however has mostly illuminated the need to get out the pencil and ruler!