Final answer:
Intensity and source-to-image receptor distance (SID) are related by the inverse square law; as the SID increases, the intensity of light at the image receptor diminishes proportionally to the square of the increased distance.
Step-by-step explanation:
Relationship Between Intensity and Source-to-Image Receptor Distance (SID)
The relationship between intensity and the source-to-image receptor distance (SID) is guided by the inverse square law. This fundamental principle in physics claims that as the distance from a light source increases, the intensity of the light decreases in proportion to the square of the distance. For instance, if the distance between the light source and the image receptor is doubled, then the intensity of the light received by the image receptor becomes one-fourth of its original value. Conversely, when the distance is tripled, the intensity decreases to one-ninth of its starting point.
This concept is particularly relevant in imaging sciences, such as radiography, where understanding and controlling the intensity of radiation is crucial. A well-known example is in the field of astronomy, where a star like Alpha Centauri A appears significantly fainter than the Sun despite having similar luminous output, due to it being 270,000 times farther away, resulting in an apparent brightness 73 billion times less.