Associate Safety Professional Practice Exam

What does a Curie (Ci) measure?

1. The volume of a radioactive material

2. The energy level of x-rays

3. The activity of radioactive material

4. The radiation exposure to humans

The correct answer is: The activity of radioactive material

A Curie (Ci) is a unit that quantifies the activity of radioactive material, indicating the rate at which radioactive decay occurs. Specifically, one Curie is defined as the amount of a radioactive substance that produces 3.7 x 10^10 disintegrations per second. This measurement is crucial in fields such as nuclear medicine, radiation safety, and nuclear physics because it helps professionals understand how much radiation is being emitted by a given sample and how that radiation could affect both human health and the environment. In terms of the other options, measuring the volume of a radioactive material relates more to physical space rather than its decay or activity, which is what the Curie quantifies. The energy level of x-rays pertains to a different concept entirely, as it deals with the energy produced when x-rays interact with matter, rather than the activity of a radioactive source. Lastly, while the Curie is important in understanding radiation exposure to humans, it does not measure exposure directly; instead, other units like the Sievert (Sv) or rem are used for that purpose, which takes into account the biological effects of radiation on humans.