Exposure is expressed in which units?

Exposure is expressed in which units?

• A. Coulombs per kilogram (C/kg)
• B. Joules per kilogram (J/kg)
• C. Grays (Gy)
• D. Sieverts (Sv)

Answer: (A)

Exposure measures the amount of ionization produced by radiation in a unit mass of air, essentially the electric charge liberated per kilogram of air. That direct link to ionization makes coulombs per kilogram the natural SI unit for exposure. Joules per kilogram is the unit for energy deposited per mass, which is the absorbed dose (a different concept called the gray). Grays quantify how much energy the material (like tissue) absorbs, not how much ionization occurs in air. Sieverts build on grays by including factors for the radiation type and tissue sensitivity to represent biological risk, so they describe dose equivalent rather than exposure.

Exposure measures the amount of ionization produced by radiation in a unit mass of air, essentially the electric charge liberated per kilogram of air. That direct link to ionization makes coulombs per kilogram the natural SI unit for exposure.

Joules per kilogram is the unit for energy deposited per mass, which is the absorbed dose (a different concept called the gray). Grays quantify how much energy the material (like tissue) absorbs, not how much ionization occurs in air. Sieverts build on grays by including factors for the radiation type and tissue sensitivity to represent biological risk, so they describe dose equivalent rather than exposure.