What is the SI unit of activity?

What is the SI unit of activity?

• A. Becquerel
• B. Sievert
• C. Gray
• D. Curie

Answer: (A)

Activity is the rate at which a radioactive source undergoes decays. The SI unit for this rate is the becquerel, defined as one decay per second. This is a measure of how active the source is, not how much energy it deposits or its biological effect. For comparison, gray is the unit of absorbed dose (energy deposited per kilogram), and sievert accounts for biological impact. The curie is an older non-SI unit equal to 3.7 × 10^10 decays per second (about 37 gigabecquerels). So the SI unit of activity is the becquerel.

Activity is the rate at which a radioactive source undergoes decays. The SI unit for this rate is the becquerel, defined as one decay per second. This is a measure of how active the source is, not how much energy it deposits or its biological effect. For comparison, gray is the unit of absorbed dose (energy deposited per kilogram), and sievert accounts for biological impact. The curie is an older non-SI unit equal to 3.7 × 10^10 decays per second (about 37 gigabecquerels). So the SI unit of activity is the becquerel.