Which of the following describes the inverse square law concerning radiation intensity?

• A. Intensity increases with distance
• B. Intensity decreases with the square of distance
• C. Intensity remains constant regardless of distance
• D. Intensity is directly proportional to distance

Answer: (B)

The inverse square law states that the intensity of radiation from a point source decreases as the distance from the source increases. Specifically, the intensity 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 of the radiation is reduced to one-quarter of its original value. This fundamental concept is crucial in understanding how radiation behaves in various contexts, including medical imaging and therapeutic applications, where proper distance from the source can greatly impact exposure levels. The law also illustrates why safety protocols emphasize maintaining adequate distances from radiation sources to minimize exposure.