How is the half-life of a radioactive source defined?

The definition of the half-life of a radioactive source is specifically the time it takes for the activity of the source to decrease by half. This measure is crucial in understanding how quickly a radioactive substance loses its radioactivity and becomes less hazardous over time. The concept of half-life is fundamental in fields such as nuclear medicine, radiological protection, and environmental science, as it helps assess the potential risk associated with radioactive materials.

Unlike other choices, which either suggest a complete decay or focus on safety and inspections, the correct definition emphasizes the exponential nature of radioactive decay. During each half-life period, the remaining radioactive material reduces to half its previous quantity, which is an essential concept for managing and predicting the behavior of radioactive sources. Understanding half-life allows practitioners to make informed decisions about exposure limits, waste management, and safety protocols involving radioactive materials.