The inverse square law relates which two factors?

The inverse square law describes the relationship between distance from a source and the intensity of radiation or energy received at that distance. It states that as the distance from a radiation source increases, the intensity of the radiation decreases proportionally to the square of the distance. This means that if the distance is doubled, the intensity is reduced to one-quarter of its original value.

In this context, beam intensity refers to the amount of energy passing through a specific area at a given distance from the source. Therefore, it directly ties into how distance affects intensity, making that relationship central to understanding the inverse square law. The other options involve factors like energy, quality, and penetrability, which, while important in radiation physics, do not specifically relate to the foundational principle of how intensity diminishes as distance increases according to the inverse square law.