Which term describes the energy absorbed per unit mass?

Which term describes the energy absorbed per unit mass?

• A. Dose rate is the energy absorbed per unit time.
• B. Exposure rate is the energy absorbed per unit mass.
• C. Activity is the energy absorbed per unit time.
• D. Dose is the energy absorbed per unit mass.

Answer: (D)

The energy deposited per unit mass is called dose. It quantifies how much radiation energy a substance or tissue absorbs, and its standard unit is the gray (Gy), where 1 Gy equals 1 joule of energy absorbed per kilogram. This relationship shows why mass matters: the same amount of energy deposited in a smaller mass yields a larger dose than the same energy spread over a larger mass. Dose rate would be the dose per unit time (how quickly the energy is delivered), not the total energy per mass. The other terms describe different concepts—exposure rate relates to ionization in air, and activity refers to the number of decays per second. So the term that describes energy absorbed per unit mass is dose.

The energy deposited per unit mass is called dose. It quantifies how much radiation energy a substance or tissue absorbs, and its standard unit is the gray (Gy), where 1 Gy equals 1 joule of energy absorbed per kilogram. This relationship shows why mass matters: the same amount of energy deposited in a smaller mass yields a larger dose than the same energy spread over a larger mass. Dose rate would be the dose per unit time (how quickly the energy is delivered), not the total energy per mass. The other terms describe different concepts—exposure rate relates to ionization in air, and activity refers to the number of decays per second. So the term that describes energy absorbed per unit mass is dose.