What is the SI unit of exposure?

The SI unit of exposure is expressed in coulombs per kilogram (C/kg). This unit measures the amount of ionization produced in air by X or gamma radiation, indicating the charge produced by radiation exposure in a specified mass of air. It is especially significant in radiation physics as it allows for the quantification of the extent to which radiation interacts with matter, particularly in the context of radiation safety and dosimetry.

The other options represent different aspects of radiation measurement. The Gray (Gy) is the SI unit of absorbed dose, representing the amount of energy deposited by radiation per kilogram of tissue. Becquerel (Bq) measures radioactivity, indicating the number of decay events per second in a material. The Sievert (Sv) is a unit that measures the biological effect of radiation and is used to indicate equivalent dose. Each of these units serves a specific purpose in the field of radiological science and dosimetry but is distinct from the concept of exposure represented by C/kg.