Associate Safety Professional Practice Exam

What does the inverse square law state concerning radiation sources?

1. Radiation energy is directly proportional to the distance

2. Radiation energy is inversely proportional to the distance squared

3. Radiation intensity decreases exponentially with distance

4. Radiation remains constant regardless of distance

The correct answer is: Radiation energy is inversely proportional to the distance squared

The inverse square law states that the intensity of radiation (or any other point source emission, such as light or sound) is inversely proportional to the square of the distance from the source. This means that as the distance from the radiation source increases, the intensity decreases, and this decrease occurs at a rate that is proportional to the square of the distance. For example, if you double the distance from the source, the intensity of the radiation is reduced to one-fourth of its original value. This phenomenon occurs because the radiation spreads out over a larger area as it travels away from the source. The principle is fundamental in understanding how various forms of radiation behave in environments such as in safety, health physics, and radiation protection. The other answers do not accurately reflect the relationship described by the inverse square law. Direct proportionality with distance, as indicated in one of the options, contradicts the law since an increase in distance from the source leads to a decrease in intensity. The exponential decrease mentioned in another option is inaccurate in this context, as the relationship is quadratic rather than exponential. Lastly, the idea that radiation remains constant regardless of distance ignores the essential principle of diminishing intensity as described by the inverse square law. Thus, recognizing the proper relationship