The SI unit for absorbed dose is

The SI unit for absorbed dose is

• A. Rem
• B. Gray (Gy)
• C. Sievert (Sv)
• D. Becquerel

Answer: (B)

Absorbed dose measures how much energy from ionizing radiation is deposited in a mass of matter. Its SI unit is the Gray, defined as one joule of energy absorbed per kilogram of tissue. This is a physical energy-deposition quantity, not accounting for how different radiations affect biology. Rem is an older unit used for dose equivalent, and Sievert is the SI unit for dose equivalent (and effective dose), which includes weighting factors to reflect biological impact. Becquerel measures activity—the rate of radioactive decays—not energy deposition. So Gray is the correct unit for absorbed dose.

Absorbed dose measures how much energy from ionizing radiation is deposited in a mass of matter. Its SI unit is the Gray, defined as one joule of energy absorbed per kilogram of tissue. This is a physical energy-deposition quantity, not accounting for how different radiations affect biology.

Rem is an older unit used for dose equivalent, and Sievert is the SI unit for dose equivalent (and effective dose), which includes weighting factors to reflect biological impact. Becquerel measures activity—the rate of radioactive decays—not energy deposition.

So Gray is the correct unit for absorbed dose.