Radiation Safety Practice Exam

What is the unit of activity known as?

1. Bequerel

2. Curie

3. Sievert

4. Gray

The correct answer is: Curie

The unit of activity is referred to as the Curie. This unit was originally established based on the radioactivity of a specific amount of radium, and it measures the amount of radioactive decay occurring in a sample. One Curie is defined as the rate at which 3.7 x 10^10 disintegrations occur per second, indicating a high activity level. The Curie is important in radiation safety because it provides a standard for quantifying radioactive sources, enabling proper risk assessment, monitoring, and regulation of radiation exposure. While the Becquerel is also a unit of activity that measures radioactive decay (one disintegration per second), the Curie remains widely used in many contexts, particularly in the United States, due to its historical significance and familiarity within the field of nuclear medicine and radiological safety. The other units mentioned, such as the Sievert and Gray, are not measures of activity. The Sievert measures biological effects of radiation (dose), while the Gray measures the amount of radiation energy absorbed by a material or tissue. Therefore, the correct understanding of the unit of activity leads us to recognize the Curie as the appropriate answer.