Which of the following options best illustrates the principle of the inverse square law?

The concept of the inverse square law is a fundamental principle in radiation physics, stating that the intensity of radiation (or any other point source of energy) diminishes with the square of the distance from the source. In practical terms, as you move further away from a radiation source, the exposure you receive decreases rapidly.

Choosing distance as the most effective protection from radiation directly reflects the inverse square law. Specifically, if you double your distance from a radiation source, the exposure you receive is not just halved; it is reduced to one-fourth of its original intensity. This demonstrates a clear application of the inverse square law, emphasizing that increasing the distance from the source dramatically decreases radiation exposure.

The other options, while related to radiation protection and exposure, do not illustrate this principle as clearly. Increasing exposure time relates to the total radiation dose received, rather than the intensity decreasing with distance. Increasing film speed pertains to the sensitivity of the film in radiation imaging, which does not connect to the distance principle. Reducing lead to decrease scatter involves materials and their interactions with radiation but does not relate to the concept of distance and its effect on exposure intensity as described by the inverse square law.