ASNT Industrial Radiography Radiation Safety Practice Test

The inverse square law indicates what relationship?

1. Intensity is directly proportional to distance

2. Intensity is inversely proportional to distance squared

3. Intensity increases linearly with distance

4. Distance has no effect on intensity

The correct answer is: Intensity is inversely proportional to distance squared

The inverse square law describes how the intensity of radiation diminishes as the distance from the source increases. Specifically, it states that the intensity of radiation is inversely proportional to the square of the distance from the source. This means that if you double the distance from the radiation source, the intensity becomes one-quarter as strong. For example, if a radiation source produces a certain intensity at one meter away, moving to two meters away results in the intensity being divided by four. This relationship is essential in radiation safety practices, as it helps professionals determine safe distances when working near radiation sources, allowing for effective measures to minimize exposure. The other options do not accurately capture this relationship; the first suggests a direct proportionality which contradicts the inverse nature; the third implies a linear increase that does not reflect the diminishing effect of distance, and the fourth completely disregards the role of distance in affecting radiation intensity.